Who ever is acting as the server needs to port forward the appropriate UDP port to their computer if they have a firewall. If the default port is being used it is 213. Otherwise it is what ever you specified in your ipxnet commands.

The ports were forwarded. Either 213 or the one that was selected by us like 19000.

Well.... we established an open-vpn connection and THEN i was able to join in dosbox via the lan-ip of the vpn-connection.

let's check the perfomance!
Afterwards i may have needs to investigate why it did not work directly via the internet-ip

Are you guys in the same country? It may sound like an odd question, but I was trying to connect with a guy in Germany a few years back and we could not get a game to connect for anything, but he could connect to a dedicated server in the USA, but in a different state than I live in. Routers between you and him could be dropping the UDP packets somewhere...it's difficult to resolve though.

We could never resolve the issue. The interesting part was we could connect to each other over TCP just fine.

We are in the same country (Germany).

It was quite funny:
First we tried the dyndns-adress again, no success.
Afterwards the vpn-ip, no success.
Again the vpn ip with added port, but 213 (which should be default) and BAM - success. I ws like "connection successfull? wtf?!? why" 😁

The performance was OK, only a few lags. As i never played Fragile Allegiance on LAN in DOS-days I don't know if this is normal or not.
And this maybe would have even been the case if the connection has been established without the vpn.

Now playing a game in an simulated OS with a simulated IPX-network over a simulated LAN on a real PC...amazing =)
I'm just curious whether we can ever manage to connect without the vpn-tunnel.

Try using my site. http://www.classicgamingarena.com

I'm sure what the latency would be like using a dedicated server here, but if anything, maybe you can find someone to setup a dedicated server there.

Oh hey, I just checked and some recently setup 2 dedicated servers in Germany through the CGA website.