FreePBX says its home but no one answers

The system is a Freepbx 2.11 distro. I have Aastra 6731 and 6757 phones, a Grandstream GXW4108. The phones are using DHCP and the grandstream is on a static IP. All have been working fine for about 2 months. All of a sudden the phones are unregistered, the grandstream is still registered, however if the Pots lines ring in the call isn’t sent to the system. The GS status page shows that the call is coming in. Using Report/Asterisk Info / Channels there is no activity when the calls come in. The Gui says all is normal. I have rebooted the system, checked whether Asterisk is running, which it is. Fail2Ban is running with no banned IPs. I defaulted a phone, got a 408 message after manually setting it up. I have I have rebooted the system, the phones, the router/firewall. It is tho the system doesn’t exist. I can lof into any device I want on the network through the interfaces.

I am stumped. Any ideas would much appreciated

Thanks

Found the problem. After all that I did, checking the Asterisk SIP settings revealed that the external IP was incorrect, and more imortantly the bound SIP port was 15060! deleteing that entry allowed the phones to connect. Strange how that might have happened, changeing the programming password now

mgknight had been added as an administrator! The system was updated some time ago This is not good