Greetings,
I'm quite frustrated with this game as I was very excited to play with my nephew and his parents.
I started off on Windows 11, playing through the Xbox Game Pass PC app as I have Xbox Game Pass Ultimate. Not only could I not join their game, but I couldn't host a game... it would just kick me out almost immediately after joining or setting up a hosted game. I checked EVERY where and tried Every suggestion provided... even ensured that my Xbox App was property connected in general for Multiplayer play. Nothing worked.
So, I did a fresh installation of Windows 10, and tried again... with a nice fresh installation of windows, Xbox App, updated drivers of all peripherals and graphics card... tried again as the only game installed on my PC and nothing... Still booted me from both being a Host, and even trying to join their game.
From what I read, I would have better luck with the Steam version... so... since most of my gaming library is already on Steam, I went and purchased the game. Same problem. Logged into Xbox with my ID, and tried Hosting a Game / joining a game, and immediately crashed to desktop.
But here is the kicker... I can play solo no problem. But that's not why I purchased or wanted to play the game. Grounded is advertised as having an excellent multiplayer experience, and even the story evolves around all 4 players being in the game... though you can play solo, it's really a multiplayer experience... and well, it's failing horribly in my experience. I have wasted hours trying to trouble shoot and tried different platforms, with no avail...
I'm running a high end system, Asus ROG Strix Z590-E Gaming Wifi, Intel 11th Gen i7 11700k, 32 Gig's DDR4, EVGA 3090 Geforce card.