Me and some friends used to play Starfleet Command 3 online but this was years ago.

I recently rediscovered this game and would like to play it on a multiplayer server with others, is there a server that runs this game ?
If not what kind of server would you need to run SFC 3 ?

Mmm, it will be hard to find players like this in general.
Maybe check if there's some dedicated site\forum\discord?

One option is https://gameranger.com/

"Starfleet Command III" is listed as supported.