I currently downgraded from 200Mb to 50Mb just to save some money for a month or so and now by having 50 down/3 up xbox live is lagging.
Current set up is superhub 2 AC in modem mode with a asus rt-ac68u router which is a kick **bleep** router. On average i have 10-24 devices on the network including 4 xbox one's. Every thing is hard wired with cat 5e only phones and tablets are wifi
ports have been forwarded and xbox recommend a minimum of 3Mb down/ 0.5Mb up but still laggy on the 50/3 line.
I appreciate i need to watch how much bandwidth other devices are doing but a good example last night only had 2 xbox one's on line as me and the step son was trying to play star wars battle front but had lag issues and disconnecting from game
If i could change back to 200 then i would but can't yet as every package change is 1 month so would have to wait till 23/04