Hey there, I also got similar shader errors, "Microsoft Media Foundation video decoding to texture disabled: graphics device is Null, only Direct3D 11 and Direct3D 12 (only on desktop) are supported."
However, I did a clean install of the server files (and verified), installed the C++ redistributables, but the error unfortunately still popped up. Did a separate install on a second computer but still can't get it working, even with the in-game created maps (Navezgame & others) and with the mods completely removed. The maps worked completely fine on single-player.
https://pastebin.com/i1QK3AJR