Accessing and using Microsoft Teams on smartphones and tablets across platforms
FWIW, I use Pi-Hole to reduce data theft and privacy violations.
It appears Teams needed to connect to...
mobile.pipe.aria.microsoft.com
in.appcenter.ms
...so I whitelisted these; still no joy.
Switched to cellular data, authenticated, then switched back to WiFi.
Teams may also be attempting to connect to other URLs.