My internet is good but my gaming speed is bad

[SizedMouse9]

I have a problem because I have done several speed tests and all of them have an average of 30mbps download and around a 10 upload but whenever I get on games my ping jumps up to over 100. One of the problems is I have a usb wifi adapter instead of ethernet or even a wifi card (which I cant get due to my motherboard) but even on my xbox I still get really bad speeds. Also my internet fluctuates a lot so one moment everythings good and the next its bad, Is there a fix to this?

 

[sizzling]

Can you use power line adapters instead of WiFi? I have found they significantly improve the ping compared to WiFi.