https://www.gametracker.com/server_info/68.232.172.197:27960/

People typically play from 9-11 PM EST. Server is in Chicago, IL.

Mod download links:

http://www.whodah.com/Quake/Files/threewave_16_full.zip
http://www.whodah.com/Quake/Files/threewave_17_update.zip

extract both zip files to Quake 3 directory, not baseq3.