A friend and I just purchased BG last week to play through it together in multiplayer, but he has a MAC and I have a PC. Both are recent hardware and operating systems. Having played NWN for years, I had hoped it would be similar and a fairly simple thing to accomplish, but so far, no love.
In an attempt to host, I began by opening the router ports suggested in the sticky (2300-2400, 6073, 47624).
When we tried to connect the differences in the MAC version of the game (v1.3.2053) and the PC version of the game (v184.108.40.206) became apparent. By sharing screenshots, we noticed that the multiplayer screens are very different and he sees a very different set of options. I was counting on using the Direct Connect option and providing my IP for him to go directly, but he doesn't have a Direct Connect option.
We also noted that he and I don't see the same set of available multiplayer games being served so it's unlikely he will be able to connect that way.
We tried the Virtual VPN as suggested on the sticky in the Multiplayer forums, but that didn't help either.
We also tried to have the MAC player serve and the PC player client in but the MAC player has an ipv6 IP address and this didn't work, either.
NWN doesn't have a Character Arbitration page, one player just starts a game and provides an IP for direct connection (the gamespy servers went down long ago) and players log in via Direct Connect. Should I be waiting for him in the Character Arbitration page or just go all the way in and wait? Do I need to populate more than one character in that page for a multiplayer game?
I think I could use some (more) detailed instructions on how to serve a game and definitely better instructions on how to client in from a MAC with completely different screens.