Frequent Line:Unregistered error on Polycom phones

[BikeShopAdmin]

I have a Polycom vvx411 and a bunch of Polycom vvx250's that all provisioned just fine. The one issue I'm having is that on the vvx411, every 10 minutes or so (or less, just a guess) the phone will show a Line:Unregistered error for about a minute, and I won't have a dial tone or phone service during that time. When I click the info button, I get a "Line Information" screen that says "Line 1: BikeShopAdmin (Not Registered)" and below it a server ending in .zoom.us that also says "(not registered 0)" and below that, a really long AOR number ending in zoom.us.

I'm actually having this issue with the vvx250's as well, where the dial tone/service is cutting out every ten minutes or so for a minute, but I don't think they're showing the "Line:Unregistered" error, but considering the symptoms are the same, I believe the root cause the be the same. If anyone has any ideas, I'm all ears!