http://www.pcgamer.com/gog-releases-another-multiplayer-update-for-the-original-star-wars-battlefront-2/

Star Wars: Battlefront 2 (note the colon, to distinguish it from the newer Star Wars Battlefront 2) was released in 2005, and so it was an honest and very happy surprise when an update was released a few months ago to restore its disabled multiplayer support. Earlier this week it was updated again, this time with a patch that promises "minor bug fixes and optimized performance." 

The minimal patch notes cite three fixes as being particularly important: