Been happening since about the time crossplay was introduced. Enduring error that occurs when a server is loaded with too many mods it seems.

I've been playing the new vietnam servers for a month, that's a map, some weapons and some outfits. Ran fine until they added an AH1 Cobra mod yesterday.
This issue is really really persistent and basically keeps Reforger unplayable for myself outside 32 players vanilla which is pretty sad for an ARMA game.

Reinstalled twice, emptied mods and redownloaded twice. It's not a common issue it seems but I've been milsimming for 10 years and not getting to play this is heartbreaking.