I was thinking the same thing. Our SIP trunk provider Flowroute doesn't have any active registrations.
My friends URL is https://12xx.3cx.cloud and it's working fine.
I'm in the same boat. 3CX has been working fine for about 5 months and all of a sudden at about 10AM CST it stopped working. I tried logging in with my memorized user and it won't allow me to log in. I tried an incognito tab as well and no luck. The forgot password feature is not sending out...