Rather odd Multiplayer problem, hoping to get some help

I've made a post on the steam community describing the problem here

My network is kind of awkward, but I don't think its the problem, mainly because SE is the only game I've had problems with that has been attributed to my network setup. If it is indeed the dreaded MTU issue, then that sucks but is not something I can change at this time.

Essentially, I use my phones hotspot for home internet, and to get around strict CGNAT and provider imposed speed throttle, I rent a VM on linode and host a wireguard tunnel, use IPTABLES masquerade and ipv4/ipv6 forwarding and pass all of my hotspot traffic through that tunnel.

Basically, I'd like to play SE MP with a friend on steam. SE single player works fine, vanilla and modded, on my pc. But the moment I joined his hosted instance I ran into a problem. I seem to connect to his instance fine, can pull up the player list and see him, his faction info etc. But I spawn into an empty skybox, with no body, and unable to open any of the menus one would use to spawn into the game.

No respawn menu was presented to me, despite 'Enable autorespawn' being disabled in the instance setup. Pressing backspace does not bring up the respawn menu, pressing ctrl + space doesn't enter spectator mode, pressing K doesn't bring up factions menu. the only thing that does work are the menus available through the escape key (options, player list, etc) the blueprints key, and the admin spawn and other such debug menus.

Thinking that it must be a problem on his or my end, i tried to connect to the public server Keen NA #1-3 with the same result, making me think it was a problem on my end. every server I connect to, modded or vanilla, I just end up stuck in an empty skybox, unable to do anything. I don't get disconnected or anything either, I just cant seem to do anything.

Is there any further testing I can do?

I'd appreciate any help you can give me on this.