Do you have any ports blocked in your configurations? Even disabling the Firewall on many SOHO (Small Office Home Office) routers can still leave the ports being blocked even though the Firewall is offline.
Depending on your router, it may be under "Virtual Server" settings in the software. More than likely any Port Forwarding configuration will be under the WAN settings and not the WiFi.
What model router are you using? Is it a Modem/Router combo that's provided by your ISP? Or are you utilizing a Modem and Router separately? If the former you may not have complete access to your settings.
~Leo
EDIT: Reading more into your posts, it appears your router is the culprit considering it was fine before you replaced it. If you can provide the model, I can look into a bit and see if I can help you out. I'm always on-board for a Network puzzle.