UT99 Master Server Guide

Epic is turning off master servers for a number of older titles including UT99, UT2004 and UT4 Alpha.
More info in this article.

But UT99 is in good hands as custom servers have been running for years with 333 Networks Master Servers.

Instructions for connecting Unreal Tournament to the 333networks masterserver.

Game Client Configuration

Before making changes to your configuration, make sure to close your game first. Once you have located the configuration file (UnrealTournament.ini) open it with a text editor of choice and find the [UBrowserAll] section. In this section, you replace the old GameSpy and Epic entries with one or more of the 333networks-affiliated masterserver entries

[UBrowserAll]
ListFactories[0]=UBrowser.UBrowserGSpyFact,MasterServerAddress=master.gamespy.com,MasterServerTCPPort=28900,Region=0,GameName=ut
ListFactories[1]=UBrowser.UBrowserGSpyFact,MasterServerAddress=utmaster.epicgames.com,MasterServerTCPPort=28900,Region=0,GameName=ut
bFallbackFactories=True

[UBrowser.UBrowserMainClientWindow]
bKeepMasterServer=True

Change to:

[UBrowserAll]
ListFactories[0]=UBrowser.UBrowserGSpyFact,MasterServerAddress=master.333networks.com,MasterServerTCPPort=28900,Region=0,GameName=ut
ListFactories[1]=UBrowser.UBrowserGSpyFact,MasterServerAddress=master.newbiesplayground.net,MasterServerTCPPort=28900,Region=0,GameName=ut
ListFactories[2]=UBrowser.UBrowserGSpyFact,MasterServerAddress=master.errorist.eu,MasterServerTCPPort=28900,Region=0,GameName=ut
bFallbackFactories=False

[UBrowser.UBrowserMainClientWindow]
bKeepMasterServer=True

After selecting and adding masterserver entries, it is important to set the value for bFallbackFactories to False. Otherwise, the entries that you removed will be added back when you close your game.

Additionally, you must set the value bKeepMasterServer to True to prevent that your configuration will be cleared and restored to the default settings when you close and restart your game.

Restart your game for the changes to take effect. The first time that you restart the game, close and re-open your configuration file to see if the changes persisted. Go to “Multiplayer Games” and see whether the UBrowser now lists online Unreal Tournament servers.