Access internal web server from inside network

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 (this changed in the last few days) by domain name.  I have other port forward mappings and those work fine.  This is only affects ports 80 and 443. If I set up forwards on my internal router to 80 or 443 on my web server from 81 or 444, I can access the webserver from inside the LAN via those ports (forwarded on the xFinity gateway to my router). So this is only affecting trying to forward 80 and 443 on the xFinity gateway and only in the last week.