Ack. Through some testing I've found out that my ISP blocks incoming connections on port 53.
This is necessary for the server, as the basics of how it works are:
First, in your BBA settings on your gamecube, you set it up just as you normally would to connect to your network / the internet / sega's server. You then change your DNS settings to my server. DNS is what tells your gamecube that (an example here) pso.sega.net = sega's IP address. The server I'm hosting has a DNS entry instead map pso.sega.net = my IP address.
Anyway, this process runs over port 53 - the standard port for DNS. I've come up with a workaround that would work with a PC, but I'm not sure how the networking works in the GC. I can't test that, as I need it to come from an IP address other than my own. If someone would be willing to test it to see if it'll work, that'd be great. I can PM out the necessary details if anyone can help. You'd need a copy of PSO Ep 1 & 2 (US version, and not plus - just vanilla to test this), BBA, and a bit of knowhow of how to set up the GC on your network.
Also, if this doesn't pan out (Charter. my ISP sucks BTW), someone else could host a server, or there are a couple of other stable private servers out there. The main one being this one:
http://www.schtserv.com/Either way, I'd like to get this running, as it'd be pretty sweet to play PSO with cool people again.