Guess you're right and it is the tor service.
https://community.umbrel.com/t/tor-stuck-at-bootstrapped-30-umbrel-1-7-3/25271
https://community.umbrel.com/t/tor-broken-on-all-umbrel/25275
Thing is, the update to 1.7.4 should have fixed it, at least it seems it did for others, not for me though, I still got no tor connection, same problem as in the first link, stuck at Bootstrap 30%.
I was wondering why more than usual lightning-channels were offline for the last couple of days, now I know why.
Still no idea what todo about it though, if the update supposed to fix the issue didn't fix it.
To your questions:
Bitcoin App shows 0 Tor peers, not that it matters anymore.
SSH? So far I've only used the Terminal from the dashboard, but I guess I can PuTTY my way in, too.
Hardware: ThinkCentre M70q, i5-10500T, 32GB