Trouble logging in

I tried the zoom test & it works fine, but when I log in using the app on my PC - it tells me that it's unable to connect to the network (even though I am online),  check your network connection & try again.  I tried uninstalling the app, restarting the computer, turning wifi off & back on again.  I also tried logging into zoom using firefox & MS Edge, but I receive the error messages:  error: http 503 service unavailable & error: http 503 error respectively.

I actually used zoom for a meeting an hour ago.  Logged out & now can't get back in for my next meeting.

Any help / suggestions would be appreciated.

Thank you.