Upgraded Wifi = Worse Experience

Somehow I seem to have gotten the short end of the stick on this one. I used to have 6mbps of internet and for the most part it at least worked. I have upgraded to 75mbps, and the internet seems significantly worse. How does it go from 6-75 and become a worse overall experience. You can stream and it says that it's usually running around 40-50mbps, however you can't even play a game on the phone. Why's that? My ping is a constant 300 if I try to play on my Ps4, and we have received 2 wifi extenders. My ping with 6mbps was around 150, sometimes it would rubberband and go to 999. However with an upgraded service the experience shouldn't in any way be worse. Overall, when running a diagnostics test or even a speed test, it shows that the internet is indeed better... However it is in fact WORSE!! What can I do to make it able to be possible to even play a phone game, let alone on a system? One would figure that with better internet that there'd be better connectivity, not overall worse. Livid is not the word to describe how upset this makes me, Loathing is not the word to describe how much I absolutely hate how this works. Took 2 steps forwards just to move 3 steps back.