If you’re behind a proxy server that inspects traffic you’ll have to enable an environment variable. Not ideal and I’m looking for other options but its documented here. Unity Hub not working with Browser Login [Please Help] - Unity Forum
Regarding 3.3.0 you can stop it from auto-updating though I would say keep an eye on versions.
Locate the app-update.yml file in the Unity Hub\resources directory
Edit this line
url: https://public-cdn.cloud.unity3d.com/hub/prod
to
url: https://public-cdn.cloud.unity3d.com/hub/prod/noupdateforme
Effectively you’re pointing the repo to a non functioning path and it won’t give a peep about updates.