Putting aside 20.4 we need to define “a mess”, as I said earlier my server works fine with 5 player. Just got off about 30 minutes ago.
Fine to me is the game runs with minimal stutter and rare instances where a player drops for whatever reason. I expect to frequently see zombies, I expect a large world 10k minimum, I expect good sized hordes, I expect to have fun playing.
I do not expect 60+ fps, I do not expect any game to be bug or trouble free, I do not expect (however I’d love to have it) hundreds of zombies on the screen at once.
Maybe you simply have higher expectations than I do and that’s okay. Look for something else to play if 7D2D isn’t meeting your expectations. There are plenty of other things to do.