Extensions unregistering and registering

@BlazeStudios, you are correct it could be lots of things, but there is a known issue with Asterisk 11.20 that pretty much exactly reveals itself as the complaint identified by OP. The fix is to downgrade until 11.21 is available for the Distro (or switch to Asterisk 13). In this case the forum users get the benefit of @dolesec’s experience as the head of Sangoma’s FreePBX support team.

Another thread: