@urusan
Oh, there sure are! Lots of modern source ports that support original game files: some are more faithful to the original gameplay, some are more experimental. I remember having a lot of fun playing Doom Legacy in early 2000s — in addition to modern network stack it had lots of graphical improvements like transparency and dynamic lighting. I didn't keep track since then, but I'm pretty sure that there are Doom engines that do even more amazing thing now.
@jens
@m0xee @jens It looks like you are right https://doomwiki.org/wiki/Doom_networking_component
Apparently UDP is supported? https://doomwiki.org/wiki/How_to_play_Doom_online_multiplayer
It also sounds like there are some modern re-implementations with more modern networking.