Over the past few weeks now I have had constant disconnection from Xbox live and lag during games before being kicked from the lobby or games such as FIFA and Modern Warfare etc. Although my download and upload speed are both high with low packet loss and good WiFi strength I still can’t seem to play any online multiplayer games without being disconnected.
I'm having similar problems at the moment with my Wi-Fi and my son being kicked off Xbox Live. The speed test shows I'm getting what I would expect but it disconnects every 10/15 minutes for about 1 minute then re-connects. Then it just repeats this throughout the day. This is across all my devices, not just Xbox Live. Smartphone reverts to 4G, Alexa doesnt respond...so frustrating as, like you said, I've only had this problem for about 2 weeks now so something has happended somewhere. I've had a new router but that didnt make a difference. Curently waiting for some more help so if I get anywhere I'll let you know!