HI
Is this error still occurring?
Where are you trying to change this ip address? You cannot change the ip address of the 3CX Server from the 3CX Management console.
The 3CX SIP SERVER gets the IP address based on the query it makes to the Windows network stack. What the stack gives, we take into account.
If you want to change the ip address of the server, go to control panel and change the network ip addr to a static one and restart the machine.
Upon reboot, 3CX will query again for network interfaces and based on what windows tells us, we will apply the new settings.