Try this:
Right click the network icon in your system tray -> open network and sharing center -> "Change adapter settings"(on the upper left of the window) -> Right click your adapter -> Click "Properties" -> Choose IPv4/TCP -> Click "Properties"
Should look like
this.
Leave the IP Adress on automatic.
Set DNS manually from there. Try "8.8.8.8" that's google's.
Then check your speeds. (Both on your PC and your Phone for comparison)