Hosting an RTCW game on Windows 10

So I'm trying to host an RTCW game and nobody seems to be able to connect to it via internet. I've set the port forwarding settings as per https://portforward.com/return-to-castle-wolfenstein/ and still nobody can connect. Strangely my brother and I played Quake 3 months ago and I was able to start a server and he was able to connect with no setup needed. What does it take to just host a game of RTCW now? I'm doing this using the iortcw- thought I also tried it with the steam version and the same problem occurred. Is there something more to this than port forwarding?