I'm having the same problem with my OBi202 as of Sunday, June 13, 2021 at 3:00 PM ET. It has been pretty reliable for four years. But starting Thursday, June 10, 2021 at 11:15 PM ET, I have been receiving emails alternately reporting the service is offline because the device is not registered, and then later the service is back online because it's registered, even though I didn't register or change anything.
Today when I logged in to the Device Configuration interface, it says "Registration Not Required." I've tried updating the Google Voice credentials, and I've tried deleting and re-adding it.
But I still can't make OR receive calls. When people try calling me, it just rings forever, but never rings on my end. When I try placing a call, it plays the old-fashioned "number out of service" tones and says "The number you dialed... XXX-XXX-XXXX... has not received a response from... the service provider." It seems like an intermittent server-related issue that began last Thursday night.