Do you have added a special DNS server in your Linux network settings?
Open shell and run this sommand:
grep "nameserver" /etc/resolv.conf
Do you use a web/DNS filter in your DSL modem or router?
On which domain/URL does DNS_PROBE_FINISHED_NXDOMAIN error happen?
Can you please run in terminal/shell these commands each (please post output with </> button here):
nslookup vivaldi.net
nslookup vivaldi.net 1.1.1.1
nslookup vivaldi.net 8.8.8.8