A sudden issue on a working system:
PJSIP endpoints register momentarily, then drop off as Unreachable. SNGREP shows all inbound packets to Asterisk flowing correctly, but Asterisk not sending and responses to those packets. All REGISTER, NOTIFY, OPTIONS just fall on deaf ears. However, outbound REGISTER packets from Asterisk to trunk providers complete successfully, so Asterisk can communicate out.
A test device in my office seems not to encounter this problem, only the customer’s site. But the internet is up and fast, and I was actually on-site for a different issue when the problem started. No new router, switch, config changes, etc…
Weird, what could it be?