Vivaldi not syncing

[genosensor]

I worked at this .org for 24 years
Network access is very open here in comparison with most large companies.
I have NO other issues with access to other public sites and services from the corporate net.

There may well be something here that is not standards compliant, but, I suspect, this breakage is very common.

I'm willing to help pinpoint the issue if you can provide some tests to run at my end.

Weirdly, I found that sync would NOT connect even if tethering to my T-Mobile phone.