Route your belts freely underground.
Mods introducing new content into the game.
Augmented or new ways of transporting materials - belts, inserters, pipes!
After placing enter/exit parts on ground and entering "underground view" i don't see any underground conectors.
Obviously it works for me and most people, so it's probably a mod conflict. :) Can you post a savegame somewhere so I can download and look at it?
Nah, it works actually.
I just didn't notice there is new item and tried connect vanilla underground belts. Sorry. :)
Well, that would do it. :D I'll add a screenshot pointing out there is a new item.