I tested every case, ethernet to wireless, ethernet to ethernet, and wireless to ethernet. Computers are not in Lan, each is 2km away. I can't find that option in router. Thank you for quick respond, it looks like it's not a problem in us (blueprints).
Maybe we will have to look into a different solution to run pings. I really don't know the percent of routers that will allow ICMP pings or not.
If your game will run mostly dedicated servers, the method will probably work better because then there's usually a direct connection or forwarding involved. The dedicated server I test with has been working well. It does take a few seconds to display the ping, though.
But if you plan on running servers hosted by local clients, this might not be the best solution if most routers in the wild won't respond to ICMP requests. Good luck