The host creates a Room Code and then shares it with friends. Join users enter the code and receive IP:PORT.
Mode Port-forward = classic. Mode VPN = fallback (Tailscale/ZeroTier/Hamachi).
To play games you need:
IPX Wrapper,
DOSBox,
DOSBox SVN,
Cnc-Ddraw,
DxWnd,
IndirectSound,
IPX-NullModem Server.
Abandonware games that are already prepared for the IPX Web Lobby can be downloaded :
HERE.