Bypass router, see if your cable/dsl/fiber/etc modem requires port forward also.
I have seen in one scenario the ISP was using a single public IP for over 300 people....which caused the nat type of consoles to be strict\type 3\etc instead of public/open. MOST LIKELY it is not the issue, but if all else checks out, it's an avenue to investigate. Mind you, if you have comcast, xfinity, google fiber, directTV, att, time warner, cox, or any other name brand internet, instead of some backwoods internet service for rural areas, this would not apply at all.