Phones randomly don't ring

I’ve been having a problem for the last 5-6 days on our FreePBX server where no phones ring randomly.

When calls come in it goes to a ring group and then an IVR. Randomly it’ll still accept the call but no phones ring and it goes straight to the IVR. Dialing any extension from the IVR takes you to the unavailable voicemail. Reloading chan_sip gets it going again, sip reload does not. It will start working on its own again too eventually.

The Asterisk CLI doesn’t show any activity when this happens although it is responsive to commands. Running sip show peers during this time shows all phones registered.

I just upgraded to FreePBX distro 5.211.65-10 last night. This is on a server running in our office so no NAT issues with the phones.

Any help would be greatly appreciated.

I think I found the issue. Sip debug was showing 401 unauthorized occasionally from our provider. I ended up forwarding ports for my provider’s IP to our PBX and routing by IP instead of registering. Haven’t had a failure for about 30 minutes when testing with about 5 calls per minute.