Multiplayer with VPN not working

[danielleedawson]

I am trying to play openttd multiplayer with my son who is 100 miles away. I thought it would be simple for us both to use a VPN so we both appear to be on the same LAN. But what happens is, he can see my server on the list (in non-advertised mode) but the join button does not work. We tried Hamachi as well with simulate behaviour. Does anyone know what we can do about this? Thanks

[planetmaker]

You need to use the same version of OpenTTD. If that's the case, then the answer very likely is: configure your routers and your VPN correctly. Notably it means that the server's router has to have port-forwarding enabled for the ports needed by OpenTTD for TCP and UDP and the PC's firewall (if any) has to allow incoming connections to those ports.

the default port is 3979, but you can change it to anything you like when you start a server. If you set up your own server behind a router, you need to forward both TCP and UDP on that port.
Communication with the master-server works via port 3979 over UDP (inbound + outbound) and 3978 over UDP (outbound)

[danielleedawson]

Thank you for your reply.
I hope this isn't a silly question, but doesn't using a VPN avoid the need for any port-forwarding?
Thanks

[jfs]

Yes using VPN should mean you shouldn't need to forward any ports. You still need to check any firewall/security suite software installed on your PCs if they potentially block the connections.

[rowdog]

I suspect that the master server is showing your router's external ip address rather than the ip address your server uses with the VPN. If that's the case, you can tell your son your server's address in VPN and he should be able to connect to that by using the -n command line option.