Unable to connect to web server inside my network with port forwarding.

I have  a web server inside my network.  I've set up port forwards to access it from outside.  I have no problem accessing the server on ports 80 or 443 (http or https) from outside my LAN by my domain name.  I can no longer access the web server from inside my LAN by domain name.  I have other port forward mappings and those work fine.  This is only affects ports 80 and 443. This is only affecting trying to forward 80 and 443 on the xFinity gateway and only since I got a new Comcast Modem.