There are so many points of failure...
Something suckling away at your bandwidth locally can cause packet clashes at your router, which can result in reduced quality of service. Things like web browsing and such wouldn't really notice issues like that, but games are far more sensitive to it, EU more than others unfortunately.
Then there is how you're connected, I'm on some horrible frankenstein of copper from the house to the local cabinet, then fibre from the cabinet to the exchange, so things aren't always that great.
Then, if you ISP is crap, you will have too many transport hops from your first isp node to the EU servers, again adding to the potential of loss of packets.
To help resolve..
I tend to take all WiFi devices that have access to the internet offline as much as is feasible, this does help. What doesn't help is TV and Sky are routed through my xbox one, so all three are on the network, so is my Three home signal box
