OK, assuming I'm looking at this right,
your IPCONFIG.DAT is:
also, within Open PS2 Loader you should set your PC's IP address in it. Microsuck XP SP3 likes to use port 445 as well.
192.168.0.10 255.255.255.0 192.168.0.1
You can keep your firewall up and running as long as you make a hole in it for your network range that you know you'll use.
You don't have to use a NAS, but it could help cut down on possible issues. if you have a spare PC, just install FreeNAS. If you do, let me know. that software is bitchy with open ps2 loader I have the settings you would need.
If you need help, post a question in the
forums, not my PM inbox. Thank you.