Port Forwarding enables remote devices on the internet to be accessed even when they are not on the same network.
The ports that need to be forwarded in the router depends on the recorder model.
Speco Player app uses the Network Video Port and web port forwarded. (default network video port is 5445 and default webport 80)
Speco Blue uses P2P, check Speco Blue ports on this Knowledge based article.
Speco Gray: P2P or Port 9000
Speco One: Port 37777