It doesn’t need to be. If his grandfathers computer is connecting to a “hub” server and is always connected, it will work. Alternatively, if @codetrotter need

It doesn’t need to be. If his grandfathers computer is connecting to a “hub” server and is always connected, it will work. Alternatively, if @codetrotter need to do the connecting, you can also setup wire guard to use a dns name, which could be dynamic. On the VPN side, it would be a static IP though…