@cryptpad
In the end, so it seems: it's me.
For whatever reason, current version of #MullBrowser from @fdroidorg does not work.
I've tried DuckDuckGo browser (again F-Droid) and it works fine.
Also @monocles@privacybrowser work, once enabled JavaScript and DOM!
For PC, I thin they updated something to office VPN... 😭
Sorry for bothering, folks.