Warframe can use UPnP or NAT-PMP in order to automatically open the ports needed for playing games and communicating with friends.

WARFRAME USES UDP PORTS 4950 AND 4955 (or whichever ports are set at the in-game options)

If you are not sure how to access your router’s settings, contact your router manufacturer or Internet Service Provider for instructions on how to enable UPnP or NAT-PMP on your device.