Server getting "Engine error" When anyone tries to join

Alright so I'm gonna take a guess and you can correct me if I'm wrong that this is caused from the amount of content my server has on it. It's a pretty heavy 4.7 GB of addons all compiled into 6 or 7 different addons in my collection. https://steamcommunity.com/sharedfiles/filedetails/?id=2007662575 When I add just about ANY more content to the server I get the problem where when I try to join, I get an engine error. Is there any way around this? Or am I actually just reaching the limits of the source engine.