SIPDOMAIN wrong address

We changed NBN providers and our ip address changed from 203.52.243.xxx to 203.53.113.xxx

We are using the same SIP provider

Freepbx registers fine on the new ip but incoming phone calls disconnect after approx 30 seconds.

From the logfiles every incoming phone call has the line below

[2315] pbx_variables.c: Setting global variable 'SIPDOMAIN' to '203.52.243.xxx'

This is wrong but I do not know where FreePBX gets this info from.

I looked in the web admin and have set the external address in sip settings to the correct setting but it keeps resetting the global Variable as above on every phone call.

We cannot recieve any phone call.

Outgoing calls work fine....