Greetings, I've trying to troubleshoot this problem and i also did some searching here but i have not found a solution to this problem: ever since i added another router, i can't connect from the outside (internet).
I had a DIR-815 running (in b/g/n mixed) but my IP cameras were really choppy so i decided to add a DIR-655 in N-only mode for the cameras - BIG improvement. However, since i did that, i can no longer connect to the cameras from the internet. I had port forwarding working fine with ddns from no-ip when running only the DIR-815.
I made DIR-655 the main router connected to the cable modem and set-up port forwarding looking at the way it was in the DIR-815 that was know to work. The DIR-815 is now the secondary router configured for "G-only" and 5GHZ.
I have tried duplicating the settings in both routers; enabling it in one and not the other and then in reverse - nothing! When port forwarding is enabled on the second router (and not the main router) i get a quick "can't connect" from the browser (firefox) but when port forwarding is enabled on the main router (and not the second router) i get a "connection time-out) after a few seconds. That leads me to believe that port forwarding should be enabled on the main router and not the second - but why can't i connect?
Another weird thing is that when i use some online port checking tools, they report the ports are open..??
I'm thinking it's a setting i missed when setting up the two router but i have no idea what it could be.