@Deeeco
Since it's working on a completely different connection, the issue would be either with your ISP or network equipment. Try checking your router for a firmware update. You can also try clearing the personal saved data, but I'm not very optimistic that will help. It's worth a shot though. There is the risk of losing offline saves and changes to settings you've made. Normally, those download from the cloud, but I can't guarantee this.
- Press the Guide button and then highlight the NHL 24 tile.
- Hit the Menu button. It's the small one to the right of the Guide button with 3 horizontal lines on it.
- Go to Manage game and add-ons > Saved data. Delete the file with your gamertag on it.
Let me know either of these make a difference or not.