What part of the xbox series x handles wireless controller connecdion?

what part of the xbox series x handles wireless controller and headset connection? My Xbox Series X keeps disconnecting my controllers and headsets. I've tried every single suggested fix I could find. The only thing I can think of now is putting a new part in it. I just don't know what the official part is or how to get it.

Would it be better to take it to a repair place? I don't have much money so I thought buying the part and repairing it myself might be better. Although I've never repaired one before.