Port forwarding not working with Android phone as wifi adapter

I cannot access nextcloud on my LAN network or outside. I suspect that it has something to do with substituting an old Android phone and port forwarding instead of buying a wifi adapter. I can assess it on the host pc by ‘localhost’ or but not by any other computer or typing the ‘IPv4’ address of the android phone.

I am running Kubuntu 20.04, the snap install of nextcloud, no-ip.com domain with the target IP address set to what I get when I search ‘my ip’, a router that port forwards 443 to 1025 and 80 to 1026 to the IPv4 address of the android phone. The phone is version android 7.0, port forwarding (with FWR app, it says I can’t use anything lower than 1024) 1025 to 443 and 1026 to 80 both pointing to 192.168.xx.xx (what I get with hostname -I on the Kubuntu machine)

I get no response from sudo ncat -l 443 when I type http://192.168.xx.xx:443 (android phone IP). Do you know what I can do to fix it? Also sorry if my question is garbage. Thank you.

Hi @garret45

I’m not sure if I’m getting your question right… Are you using theatreing / mobile hotspot on your Android phone to connect your server to the internet? If so, port forwarding won’t work because your phone won’t actually get a public IP address. Most mobile providers, if not all, use Carier-grade NAT (CGNAT) which means your phone gets an IP address from a private IP pool in your mobile providers network, which then get translated to a shared public IP address. Similar to how local IP addresses work behind a router in a home network.