I replaced my trusty DIR-655 with a new DIR-865L today. Automatic setup went smoothly, and after that was complete I created/enabled a mydlink account, updated my firmware to 1.03 and set up my various DHCP reservations. After that I verified that after restarting the various PCs they were getting the IPs I had allocated for them and then I entered the port forwarding rules into the router. I added port forwarding rules for my homeserver, minecraft server, and steam server. These are the same DHCP reservation IPs and Port Forwarding rules I used successfully on the DIR-655.
Unfortunately, I have not been able to access my computers from the internet. I verified that I was able to access the web site on my homeserver and the minecraft server via another local computer using the lan IP:port - so the basic functionality works. I also verified that the WAN IP address in the router WAN Status page is valid so I'm not suffering from the multiple routers issue. I went to the routers firewall settings and switched both to "endpoint independent" for the NAT filtering. I played a bit with DMZ and that didn't seem to help either. I have rebooted the router. My Comcast modem is an ARRIS TM822.
Any other thoughts for additional troubleshooting?
Thanks for any suggestions.