I got distracted from my work so I made some Continuwuity propaganda. Continuwuity is a lightweights Matrix chat server that you can self-host pretty easily. Give it a try :3
It's not really designed to be a Discord replacement. It's a messaging app/protocol that can do voice/video calls. Discord is a passive state voice / video / text channel app that was designed to create spaces for different topics. Matrix has added a similar hierarchical feature as an option, but its not the same and I don't think it was meant to be.