Domain voip.nnnn.com is forwarded to 47.158.x.x (Public non-static IP of Peplink Balance 580X WAN 1) with my registrar.
Entering voip.nnnn.com in the address bar loads http://47.158.x.x/cgi-bin/MANGA/index.cgi providing access to the Balance 580X’s webpage allowing me to log into the router.
Balance 580X has port forwarding enabled for WAN1 IP 47.158.c.d port 51xxx to 10.200.x.x port 81 to access a Windows Server Internet Information Services webpage.
Entering 47.158.x.x:51xxx in the address bar loads the Windows Server Internet Information Services webpage for my Windows server.
However, entering voip.nnnn.com:51xxx in the address bar fails to load the Windows Server Internet Information Services webpage and times out.
This is just a test setup to move away from an IP address-based setup to a domain-based setup for a voip server running OpenVPN that has phones registering successfully using the IP address but is unable to use the domain address.
What could be causing the combination of the domain forwarding and port forwarding to fail when the each works independently?