How do I fix this problem?

[Cornstarch]

Port forwarding was successful, but the router returned a private ip address. This means you have an exotic network or internet provider is doing weird multi-routing shenanigans, which makes it unlikely that other players can connect.

I'm not sure what the problem is but I can't find a fix for it anywhere. 

[MrMutant]

figured it out kinda, if your using an ethernet cable you gotta set it to discoverable in your settings