One question I forgot, are you gaming on a wired pc or wifi? That will bring up its own issues if via wifi, always best if wired.
If it has to be wifi, then check if the wifi channel is being used by neighbours, if it is that can cause slow speeds and gaming issues like the lost connections you are getting.
http://www.metageek.net/products/inssider/ will tell you what channels are being used, then you can use a different one
FTTP 500 regrade from Tues 28th November