ERR_CONNECTION_CLOSED -Help

kmagick64

Vivaldi 4.1.2369.16 (Stable channel) (64-bit)
Windows 7 Service Pack 1
Fibre broadband

I am getting ERR_CONNECTION_CLOSED in VIvaldi when trying to access amazon.co.uk via vpn.
Specifically, I am in UK and if I use a vpn server located in UK I get error but if I use a vpn server located outside of the UK then no error. Also if I disable the vpn then no error.

I created a new basic Vivaldi profile and problem is same.

I tried some other browsers - EPIC, Opera and really old version of Firefox - these all work correctly with vpn wherever server is located. The Brave browser failed in same way as VIvaldi.

There is a noticeable delay before error is displayed instead of expected web page.
I don't know whether it is relevant but I see similar delay when a speed dial is clicked for 1st time - get error cannot access page then few secs later it actually loads page without further user action.

I am puzzled why different browsers with same engine work and some do not.
How should I proceed to debug / fix ?

Thanks

Pathduck

@kmagick64 said in ERR_CONNECTION_CLOSED -Help:

I don't know whether it is relevant but I see similar delay when a speed dial is clicked for 1st time - get error cannot access page then few secs later it actually loads page without further user action.

This is a known bug for the first request when "Startup With" is set to "Home Page" in Settings > General.

As for the VPN issue, it sounds like your VPN is borked, you really need to take this to your VPN provider support. I can't explain why it seems to work for other browsers.

kmagick64

@pathduck

I can try it on vpn provider but doubt they will be very interested

My initial thought was amazon.co.uk was geo blocking vpn servers in uk. However every other browser (including Chrome) I have tried works fine. The only browsers I have found to give error are Vivaldi and Brave.

To my mind that logically indicates problem is with Vivaldi - hardware software router network environment is exactly same for all browsers tested.

Maybe tracing with wireshark or HAR log will show cause of error,

Pathduck

@kmagick64 Maybe there's some caching going on, or maybe your VPN has some sort of "access list" that only allows certain browsers. Impossible to tell.

Try:
vivaldi://net-internals/#dns - clear host cache
vivaldi://net-internals/#sockets - clear and flush

Try also the troubleshooting tips:
https://help.vivaldi.com/desktop/troubleshoot/troubleshooting-issues/

Maybe tracing with wireshark or HAR log will show cause of error,

If you're able to, it might help. See if the IP address from the Devtools network log matches the one you're getting in other browsers.

ERR_CONNECTION_CLOSED means the server you're trying to connect to actively closed the connection. Basically, the port is listening, it just won't accept a connection.

When connected to the VPN, I would assume every network request goes through the VPN. See if you can use nslookup on Amazon UK and what result you get. Unless you're using one of those browser-only VPN extension things... my suggestion is DON'T USE THOSE.

You can try a telnet amazon.co.uk 443 and see what IP and if you get a connection.

You can do a curl ipaddy.net for checking if your VPN works as expected, if you have curl installed. It returns your IP and IP country.

Try the Chrome connectivity diagnostics:
https://chrome.google.com/webstore/detail/chrome-connectivity-diagn/eemlkeanncmjljgehlbplemhmdmalhdc/related?hl=en
Installs as an app, can later be removed from vivaldi://apps

As you're still on Win7, have you enabled TLS 1.2 in Internet Options? And disabled SSL?
https://knowledge.digicert.com/generalinformation/INFO3297.html#Chrome
https://support.microsoft.com/en-us/topic/update-to-enable-tls-1-1-and-tls-1-2-as-default-secure-protocols-in-winhttp-in-windows-c4bd73d2-31d7-761e-0178-11268bb10392

kmagick64

@Pathduck
Thanks for all your suggestions. Apologies for long post here as there are some HAR logs (edited) at bottom.

Try:
vivaldi://net-internals/#dns - clear host cache
vivaldi://net-internals/#sockets - clear and flush

When I tried this the clicking the button (grey) appeared to do nothing... at least there was no message confirming action had been done.

Try also the troubleshooting tips:

Yes had already been thru this. Also no AV or Firewall.

If you're able to, it might help. See if the IP address from the Devtools network log matches the one you're getting in other browsers.

I don't see any ip adresses in the netwrok log - is there a config setting somewhere?

When connected to the VPN, I would assume every network request goes through the VPN. See if you can use nslookup on Amazon UK and what result you get. Unless you're using one of those browser-only VPN extension things... my suggestion is DON'T USE THOSE.

Yes all network request go thru the vpn. VPN is Surfshark which I have found to be at least as good as some other well known ones I have tried.

nslookup is same with vpn on or off:-
C:\Users\JR>nslookup amazon.co.uk
Server: 57.172.252.162.in-addr.arpa
Address: 162.252.172.57

Non-authoritative answer:
Name: amazon.co.uk
Addresses: 54.239.33.58
178.236.7.220
54.239.34.171

You can try a telnet amazon.co.uk 443 and see what IP and if you get a connection.

I don't get a telnet connection with vpn on or off

You can do a curl ipaddy.net for checking if your VPN works as expected, if you have curl installed. It returns your IP and IP country.

curl returns correct country as I switch servers

Try the Chrome connectivity diagnostics:

Chrome Store would not let me login with normal Vivaldi profile (message said insecure browser!). That profile had virtually all privacy options off but did have several extension but all were disabled. Using clean profile got it installed. I also installed in Opera for comparison.

Running test on both browsers gave virtually same result. Both gave DNS poisoning error. Vivaldi response time to google services gave too slow error Opera gave just a warning for same. When I ping test amazon.co.uk the vpn only adds about 25%

As you're still on Win7, have you enabled TLS 1.2 in Internet Options? And disabled SSL?
https://knowledge.digicert.com/generalinformation/INFO3297.html#Chrome
https://support.microsoft.com/en-us/topic/update-to-enable-tls-1-1-and-tls-1-2-as-default-secure-protocols-in-winhttp-in-windows-c4bd73d2-31d7-761e-0178-11268bb10392

tls options are all on in Internet Options
The windows update referred to was already installed on system. However I noted that documentation stated "To apply this update, the DefaultSecureProtocols registry subkey must be added". That key was not present in my system and I have now added it.. Bit strange that a windows update does not include the registry mod as part of update...?

Lastly I created 3 HAR logs for accessing amazon.co.uk:-

Vivaldi with vpn off
Vivaldi with vpn on
Opera with vpn on

Log 1
{
"log": {
"version": "1.2",
"creator": {
"name": "WebInspector",
"version": "537.36"
},
"pages": [
{
"startedDateTime": "2021-08-19T20:01:12.743Z",
"id": "page_1",
"title": "https://www.amazon.co.uk/",
"pageTimings": {
"onContentLoad": 1207.4029999998857,
"onLoad": 1968.795
}
}
],
"entries": [
{
"_initiator": {
"type": "other"
},
"_priority": "VeryHigh",
"_resourceType": "document",
"cache": {},
"connection": "364",
"pageref": "page_1",
"request": {
"method": "GET",
"url": "https://www.amazon.co.uk/",
"httpVersion": "http/2.0",
"headers": [
{
"name": ":method",
"value": "GET"
},
{
"name": ":authority",
"value": "www.amazon.co.uk"
},
{
"name": ":scheme",
"value": "https"
},
{
"name": ":path",
"value": "/"
},
{
"name": "cache-control",
"value": "max-age=0"
},
{
"name": "sec-ch-ua",
"value": "" Not A;Brand";v="99", "Chromium";v="92""
},
{
"name": "sec-ch-ua-mobile",
"value": "?0"
},
{
"name": "upgrade-insecure-requests",
"value": "1"
},
{
"name": "user-agent",
"value": "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.134 Safari/537.36"
},
{
"name": "accept",
"value": "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,/;q=0.8,application/signed-exchange;v=b3;q=0.9"
},
{
"name": "sec-fetch-site",
"value": "none"
},
{
"name": "sec-fetch-mode",
"value": "navigate"
},
{
"name": "sec-fetch-user",
"value": "?1"
},
{
"name": "sec-fetch-dest",
"value": "document"
},
{
"name": "accept-encoding",
"value": "gzip, deflate, br"
},
{
"name": "accept-language",
"value": "en-GB,en-US;q=0.9,en;q=0.8"
}
],
"queryString": [],
"cookies": [],
"headersSize": -1,
"bodySize": 0
},
"response": {
"status": 200,
"statusText": "",
"httpVersion": "http/2.0",
"headers": [
{
"name": "content-type",
"value": "text/html;charset=UTF-8"
},
{
"name": "server",
"value": "Server"
},
{
"name": "date",
"value": "Thu, 19 Aug 2021 20:01:18 GMT"
},.

Log 2 -----------------------------------------------------------------------------
{
"log": {
"version": "1.2",
"creator": {
"name": "WebInspector",
"version": "537.36"
},
"pages": [],
"entries": [
{
"_initiator": {
"type": "other"
},
"_priority": "VeryHigh",
"_resourceType": "document",
"cache": {},
"request": {
"method": "GET",
"url": "https://www.amazon.co.uk/",
"httpVersion": "",
"headers": [
{
"name": "sec-ch-ua",
"value": "" Not A;Brand";v="99", "Chromium";v="92""
},
{
"name": "sec-ch-ua-mobile",
"value": "?0"
},
{
"name": "Upgrade-Insecure-Requests",
"value": "1"
},
{
"name": "User-Agent",
"value": "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.134 Safari/537.36"
}
],
"queryString": [],
"cookies": [],
"headersSize": -1,
"bodySize": 0
},
"response": {
"status": 0,
"statusText": "",
"httpVersion": "",
"headers": [],
"cookies": [],
"content": {
"size": 0,
"mimeType": "x-unknown"
},
"redirectURL": "",
"headersSize": -1,
"bodySize": -1,
"_transferSize": 0,
"_error": "net::ERR_CONNECTION_CLOSED"
},
"serverIPAddress": "",
"startedDateTime": "2021-08-19T19:59:38.746Z",
"time": 10478.716000000077,
"timings": {
"blocked": 10478.716000000077,
"dns": -1,
"ssl": -1,
"connect": -1,
"send": 0,
"wait": 0,
"receive": 0,
"_blocked_queueing": -1
}
}
]
}
}

Log 3 ---------------------------------------------------------------------------
{
"_initiator": {
"type": "other"
},
"_priority": "VeryHigh",
"_resourceType": "document",
"cache": {},
"connection": "5621",
"pageref": "page_1",
"request": {
"method": "GET",
"url": "https://www.amazon.co.uk/",
"httpVersion": "http/2.0",
"headers": [
{
"name": ":method",
"value": "GET"
},
{
"name": ":authority",
"value": "www.amazon.co.uk"
},
{
"name": ":scheme",
"value": "https"
},
{
"name": ":path",
"value": "/"
},
{
"name": "cache-control",
"value": "max-age=0"
},
{
"name": "rtt",
"value": "200"
},
{
"name": "downlink",
"value": "10"
},
{
"name": "ect",
"value": "4g"
},
{
"name": "sec-ch-ua",
"value": ""Opera";v="77", "Chromium";v="91", ";Not A Brand";v="99""
},
{
"name": "sec-ch-ua-mobile",
"value": "?0"
},
{
"name": "dnt",
"value": "1"
},
{
"name": "upgrade-insecure-requests",
"value": "1"
},
{
"name": "user-agent",
"value": "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.164 Safari/537.36 OPR/77.0.4054.277"
},
{
"name": "accept",
"value": "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,/;q=0.8,application/signed-exchange;v=b3;q=0.9"
},
{
"name": "sec-fetch-site",
"value": "none"
},
{
"name": "sec-fetch-mode",
"value": "navigate"
},
{
"name": "sec-fetch-user",
"value": "?1"
},
{
"name": "sec-fetch-dest",
"value": "document"
},
{
"name": "accept-encoding",
"value": "gzip, deflate, br"
},
{
"name": "accept-language",
"value": "en-GB,en-US;q=0.9,en;q=0.8"
},
{
"name": "cookie",
"value": "session-id=262-0909462-1924126; i18n-prefs=GBP; csm-hit=s-GX5KCJJA0JD6SEXCRCNY|1629404590135; ubid-acbuk=261-0513687-9846662; session-id-time=2082787201l; session-token="u/gH6K+3eLGgvlCyOB3HPjaBz+V5uY8zyuSwynQDiwKRrPNLUlL6p5yvVWBRgpqBkaDzBRNzl3p9Kc44o5Bblv+of6apCZjK/4WQ8IxkpWra5KJZ7ekk0ausa11+DTKw8aLhYq4ynnljyo7VMj8MftRHXEG2UPgMfst41EGxKLCzVcfGWHCtCiHJ/kqFz2PatEtv886iBxqitrJY4G5J1shGyaWbSXWRTcJTRrktm2LxrI2PsgnenbeOA13nWlZXvUnLGOLqEeE=""
}
],
"queryString": [],
"cookies": [
{
"name": "session-id",
"value": "262-0909462-1924126",
"path": "/",
"domain": ".amazon.co.uk",
"expires": "2022-08-19T20:23:12.226Z",
"httpOnly": false,
"secure": true
},
{
"name": "i18n-prefs",
"value": "GBP",
"path": "/",
"domain": ".amazon.co.uk",
"expires": "2022-08-19T20:23:12.226Z",
"httpOnly": false,
"secure": false
},
{
"name": "csm-hit",
"value": "s-GX5KCJJA0JD6SEXCRCNY|1629404590135",
"path": "/",
"domain": "www.amazon.co.uk",
"expires": "2021-08-26T20:23:10.000Z",
"httpOnly": false,
"secure": false
},
{
"name": "ubid-acbuk",
"value": "261-0513687-9846662",
"path": "/",
"domain": ".amazon.co.uk",
"expires": "2022-08-19T20:23:12.226Z",
"httpOnly": false,
"secure": true
},
{
"name": "session-id-time",
"value": "2082787201l",
"path": "/",
"domain": ".amazon.co.uk",
"expires": "2022-08-19T20:23:12.226Z",
"httpOnly": false,
"secure": true
},
{
"name": "session-token",
"value": ""u/gH6K+3eLGgvlCyOB3HPjaBz+V5uY8zyuSwynQDiwKRrPNLUlL6p5yvVWBRgpqBkaDzBRNzl3p9Kc44o5Bblv+of6apCZjK/4WQ8IxkpWra5KJZ7ekk0ausa11+DTKw8aLhYq4ynnljyo7VMj8MftRHXEG2UPgMfst41EGxKLCzVcfGWHCtCiHJ/kqFz2PatEtv886iBxqitrJY4G5J1shGyaWbSXWRTcJTRrktm2LxrI2PsgnenbeOA13nWlZXvUnLGOLqEeE="",
"path": "/",
"domain": ".amazon.co.uk",
"expires": "2022-08-19T20:23:12.226Z",
"httpOnly": false,
"secure": true
}
],
"headersSize": -1,
"bodySize": 0
},
"response": {
"status": 200,
"statusText": "",
"httpVersion": "http/2.0",
"headers": [
{
"name": "content-type",
"value": "text/html;charset=UTF-8"
},
{
"name": "server",
"value": "Server"
},
{
"name": "date",
"value": "Thu, 19 Aug 2021 20:23:40 GMT"
},
---------------------------------------------------------------------------------
The GET method headers on Vivaldi+ vpn do not look right? Seems like it is generating different/bad http request when vpn is active for some reason?

Pathduck

@kmagick64

Apologies for long post here as there are some HAR logs (edited) at bottom.

I had expected you to save and zip the files, then upload them somewhere. No-one (in their right mind) reads HAR logs like that...

And please use code blocks, </> icon when posting huge txt blocks like that...

like this

Or even better use a pastebin service, like pastebin.com or others. WARNING: Make sure you're not actually logged in to Amazon UK when saving the log. HAR logs contain cookie values that could be used to log in as your user.

When I tried this the clicking the button (grey) appeared to do nothing...

Yes, it doesn't give any feedback, that's normal.

I don't see any ip adresses in the netwrok log - is there a config setting somewhere?

When you mentioned HAR logs I assumed you were familiar with the Devtools. You can see the IP when clicking on the request line in the log:

I don't get a telnet connection with vpn on or off

What error message do you get? It should look like this:

> telnet amazon.co.uk 443
Trying 54.239.33.58...
Connected to amazon.co.uk.
Escape character is '^]'.
↔
telnet> quit
Connection closed.

Try also curl directly to the server:

> curl -IX GET https://www.amazon.co.uk
HTTP/1.1 200 OK
Connection: keep-alive
server: Server
date: Fri, 20 Aug 2021 07:00:38 GMT
.....

Chrome Store would not let me login with normal Vivaldi profile (message said insecure browser!).

Firstly, you don't need to log in to install extensions. Second, you have probably disabled the Web Store Google extension in Settings > Privacy.

Both gave DNS poisoning error. Vivaldi response time to google services gave too slow error Opera gave just a warning for same. When I ping test amazon.co.uk the vpn only adds about 25%

Sounds like your VPN is playing up. Ping test is not a good check for HTTP connectivity and response times.

The GET method headers on Vivaldi+ vpn do not look right?

That's because it never makes it to actually make a HTTP request, it fails before that with the error code you're seeing.

kmagick64

@pathduck

I had expected you to save and zip the files, then upload them somewhere. No-one (in their right mind) reads HAR logs like that...

Apologies - I am not a great forum user - will take note

When you mentioned HAR logs I assumed you were familiar with the Devtools. You can see the IP when clicking on the request line in the log:

OK thanks. Well in Vivaldi there is no IP - as no connection I guess. In Opera shows IP for www.amazon.co.uk same as reported by nslookup.

I don't get a telnet connection with vpn on or off

What error message do you get? It should look like this:
> telnet amazon.co.uk 443
Trying 54.239.33.58...
Connected to amazon.co.uk.
Escape character is '^]'.
↔
telnet> quit
Connection closed.

My previous comment was I think wrong. When telnet command is run (vpn on or off) there is a brief flashing message which I am unable to read (connecting...?) and then screen goes blank which I think indicates it has connected? My telnet client is the basic Windows 7. No visible error messages.

Try also curl directly to the server:

> curl -IX GET https://www.amazon.co.uk
HTTP/1.1 200 OK
Connection: keep-alive
server: Server
date: Fri, 20 Aug 2021 07:00:38 GMT
.....

Curl results -1st with vpn 2nd no vpn

HTTP/2 503
server: Server
date: Fri, 20 Aug 2021 21:57:44 GMT
content-type: text/html
permissions-policy: interest-cohort=()
x-amz-rid: BE9KMX9CMABNW9MZYBBV
vary: Content-Type,Accept-Encoding,X-Amzn-CDN-Cache,X-Amzn-AX-Treatment,User-Age
nt
strict-transport-security: max-age=47474747; includeSubDomains; preload
content-length: 7053

C:\Users\JR>"F:\Programs Misc\curl\bin\curl" -IX GET https://www.amazon.co.uk
HTTP/2 503
server: Server
date: Fri, 20 Aug 2021 21:59:55 GMT
content-type: text/html
permissions-policy: interest-cohort=()
x-amz-rid: JFAC54P6C9YJBMMFDYPA
vary: Content-Type,Accept-Encoding,X-Amzn-CDN-Cache,X-Amzn-AX-Treatment,User-Age
nt
strict-transport-security: max-age=47474747; includeSubDomains; preload
content-length: 7053
code_text

Firstly, you don't need to log in to install extensions. Second, you have probably disabled the Web Store Google extension in Settings > Privacy.

Both gave DNS poisoning error. Vivaldi response time to google services gave too slow error Opera gave just a warning for same. When I ping test amazon.co.uk the vpn only adds about 25%

Sounds like your VPN is playing up. Ping test is not a good check for HTTP connectivity and response times.

The GET method headers on Vivaldi+ vpn do not look right?

That's because it never makes it to actually make a HTTP request, it fails before that with the error code you're seeing.

Yes Google Web Store was not ticked in privacy settings. I think when I quickly read that section it was not perfectly clear if ticking enabled or disabled the extesnion.

My vpn could well be playing up but how are all the other browsers managing to work?

Pathduck

@kmagick64 said in ERR_CONNECTION_CLOSED -Help:

will take note

Now go back and edit your older huge text posting. You need the practice

Well in Vivaldi there is no IP - as no connection I guess.

AFAIK to get a CONNECTION_CLOSED you need an actual connection first, and to get a connection you need an IP. But maybe something on your system is closing the connection (or socket) before it can even open.

When telnet command is run (vpn on or off) there is a brief flashing message which I am unable to read (connecting...?) and then screen goes blank which I think indicates it has connected?

Something must be seriously wrong with your system. I have no idea what you just described there. Maybe make a screen recording of it?
Easy to use: https://getsharex.com/

Curl results -1st with vpn 2nd no vpn

HTTP 503 means "Service Unavailable". Looks like Amazon changed something and now I need to provide a UA string to get a 200 OK.

$ curl -IX GET -A "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.134 Safari/537.36" "https://www.amazon.co.uk/"
HTTP/2 200
content-type: text/html;charset=UTF-8
server: Server
date: Sat, 21 Aug 2021 10:43:30 GMT

how are all the other browsers managing to work?

I have no idea. That's kind of what you will have to figure out

kmagick64

@pathduck

Now go back and edit your older huge text posting. You need the practice

I tried but edit is only allowed up to 3600 secs after post apparently

When telnet command is run (vpn on or off) there is a brief flashing message which I am unable to read (connecting...?) and then screen goes blank which I think indicates it has connected?

Something must be seriously wrong with your system. I have no idea what you just described there. Maybe make a screen recording of it?
Easy to use: https://getsharex.com/

My description wording was probably bad. I meant command window rather than screen. I think it connects and clears window as it starts terminal emulation.

how are all the other browsers managing to work?

I have no idea. That's kind of what you will have to figure out

Well I managed to find time for some for some further checking:-
I re-tested all other browsers and all work - including Brave which I previously said did not
Spoke to Surfshark vpn support - tried various stuff - they could not find any problem although did say Amazon Prime can be tricky sometimes (but this is just Amazon home page).
Tried another vpn app (Windscribe) which worked fine.
As it seemed problem was specific to Viavaldi + Surfshark vpn combination resorted to Network Monitor tracing to look for clues.
DNS lookup looked like it could be a problem ( ip address was empty on devtools). On my lan config the router specifies the DNS servers (openDNS) and the lan devices specify the router as DNS server. In the tracing I could see refs to Cloudflare DNS 1.1.1.1 (which is not specified anywhere in my network).
When I changed the DNS server settings on TAP adapter for Surfshark from obtain DNS server automatically to specifically use openDNS servers the error was gone and amzon.co.uk home page came straight up.

I am not clear why this change fixed the problem or why Vivaldi was the only browser out of all those I tried which gave the error. Also I did not need to edit the DNS server config for the TAP adapter for the Windscribe vpn to make it work correctly.
I did briefly look at how Windows (7 in my case) resolves names - which involves multiple steps with various timeouts between steps. (Windows 10 process is I understand different.).

Thanks to @pathduck for your input

.

Pathduck

@kmagick64 Good to hear it's working for you now

I guess this is why trying to troubleshooting someone else's (faulty) VPN is generally an exercise in futility. I have a personal policy of "if you're using a VPN you're on your own mate". In your case it seemed a clear case of a VPN playing up and you just needed some prodding in the right direction to realise it.

I don't use VPNs myself. They just add more complexity to something already very complicated to troubleshoot, and seem prone to all kinds of bugs. My general impression is that most of them them operate by spreading FUD ("Danger - your IP is exposed!") and some of them seem outright malware peddlers. I certainly trust my local ISP more than I trust some of these companies.

On my lan config the router specifies the DNS servers (openDNS) and the lan devices specify the router as DNS server.

I may be ignorant on VPN functionality - but I thought the whole point of using a VPN was to have all network traffic from your PC routed through it, including DNS queries? If you ask your router, it will then ask openDNS through your ISP, defeating some of the point of using a VPN. I think very few home routers have support for DoH at the moment.

I guess if you're using a VPN primarily for the purpose of security and not privacy as such, it's not such a big deal if you send DNS requests through your ISP.

In the tracing I could see refs to Cloudflare DNS 1.1.1.1

It shouldn't be the case here, but it might be good to know that Vivaldi/Chromium by default will use DNS-over-HTTPS, and it will try to detect if you're using one of the supported providers (Cloudflare include). Check the URL chrome://settings/security and make sure Secure DNS is turned off if you want to use your own DNS settings.

tr3k

Please check if you have any docker or other containers restarting in the background. Virtual network changes can cause this.