As an update, if I go into the Server app and select the Server (under Hardware) and select the Network tab, I can see that the Host Name has changed to discussion.lan
If I select Edit and Change Host Name for internet to discussion.pharmweb.net then the Host Name is updated. However, my web servers are still not accessible to the outside world (no response). Strangely, if I use Safari on the server itself and access one of my web servers (discussion.pharmweb.net) then I get the web page loaded, however, none of the other sites on the server load up. Help...
Sounds like your server's LAN IP changed.
Its important NOT to change your server's LAN address without going through a few steps.
Your server is set with a 'manual' address, not DHCP, correct?
Since you just replaced your router, did you re-enter your port maps?
Without port maps, your server is inaccessible to the outside world.
You are spot on re. IP change! The new router is a result of me moving to fibre (which has been very fast and reliable). I was assured by my provider that my IP address would remain the same but have since discoverred that my IP address changed when the router was rebooted! Am waiting for the issue to be resolved, once I have my IP address back I hope that all will return to normality...
Are you sure it wasn't just the server's LAN IP that changed?
Is it set to Manual ?
If your server is behing a router with a NAT address, then a change in the public IP shouldn't have caused that error. I bet your LAN IP changed and now you don't have port mapping correct. pherhaps the public IP changed also, but my money is on the LAN address.
If its the LAN address, there is no point waiting for the ISP.
Set it back to the address it used before and make sure the router provides NAT with port mapping to that address.
Thats all in your control, not the ISP.