I am sure you are aware of Epic shutting down the master servers for classic games, notable of which is the Unreal games (1,2, T99,t2003,t2004,2014/4) with the exception of UT3 which is coming back as a F2P on steam/gog/egs. I am using the OpenSpy master server for 2004 with a legitimate key I got from buying UT2004 on GOG. For UT99 and Unreal Gold, I am using the patches from Oldunreal. Now for 2003, I do not have it, and for Unreal 2 you need to install the multiplayer add-on since it didn't come with the base game. UT3 I used to have it, but am planning on grabbing it when it comes out as F2P so no worries there. For UT 2014/4 Alpha it will be shut down with no way to play it offline since it runs through the EGS Launcher and it uses a PAK file to load it using a protocol in a URL file which doesn't even work since I don't have Internet Explorer anymore. I got modern enhancements I will post later that will get the old games to work natively on modern systems.

For Unreal Gold and UT99, use oldunreal's patches work great and give you a lot of options.

For UT99's Master Server though I recommend 333networks since they have a good list of updated master servers.

For UT 2004, I use OpenSpy as a master server, followed by custom settings in INI that deals with modern resolutions and using OpenGL, not D3D9 which isn't even listed. i remember UT2004 having a native 64 bit binary but its rather old and broken so stick to 32-bit for the moment.

For Unreal 2, I haven't tried it so look at open spy/333networks. It makes as much sense to have multiplayer in that game as it did to have multiplayer in Deus Ex vanilla or Co-Op in System Shock 2. No real reason other than to pad the game