I've had this problem for about a year now and I still can't seem to fix it. For some strange reason, any mod I download appears in the "Server Mods" tab, despite being clientside mods. They are named, "workshop-(the ID of the mod)," and whenever I try to use the mod, it doesn't work. Along with that, I can't even join any servers that have ANY mods whatsoever.
I have unsubscribed from all mods and turned auto-subscribe off. It didn't work.
I have reinstalled the game. It didn't work.
I have verified the integrity of the game files. It didn't work.
People have told me to go into the files and go to C:\Program Files (x86)\Steam\SteamApps\common\Don't Starve Together\mods and manually delete the mods in there. However, the mods just don't appear in the mod folder. Nothing seems to work for me.