Massive fps drops on xbox series x

Tried all settings. Some classes are much worse than others and playing with other people makes the problem 10 x worse. I play stormweaver sorc and gas arrow ranger and my friend plays a grenade merc. It's unplayable with him in my party. My Internet is running at 400+mbps. 7ms. Maps are the worst. Breaches especially and delirium. Completely screws me as soon as the waves move or the mirrors move. It's an mmo game I can't play multiplayer atm haha. I tried resetting cache and everything on xbox too just to make sure it's not my side. So if this could be looked in to that'd be awesome. I'd like to play with my friends and on my own without stutter and fps drops. Thanks!