Is it up and running through GOG? I'm sure the official servers have been taken down a while ago.

I created a thread for the entire series: https://www.gog.com/forum/soldier_of_fortune_series/how_does_multiplayer_work

Official master server was shut down years ago. That is why when you go to multiplayer server browser nothing pops up in search results. Just google "Soldier of Fortune 2 master server 2018", it basically comes down to adding a line or two in your config.cfg file"
set sv_master2 "master.1fxmod.org"
set sv_master2 "178.62.14.201"

there are 50+ servers at the moment.

You can also manually join servers by finding their IP using Gametracker website (https://www.gametracker.com/search/sof2/?searchipp=50#search)
So in the end it is a bit of a fuss but it is definitely worth it, SOF2 has one of the best multiplayer I've ever played.

What are the player numbers currently? Frack, what a blast from the past this could be!