RE: slow internet loading, slow youtube response: Dell 5558
If your using 5Ghz band and not 2.4 Ghz your going to have limited range and speeds will drop off quickly. If your going to be away from router very far like in another room. Your better off with 2.4 Ghz.
I have the Intel 3160 and it works pretty well but make sure to have the latest drivers, maybe even try the Intel drivers. If you really want good 5 Ghz performance and range you need external antenna's on router. It's possible your antenna lead is disconnected on your notebook card, so you may want to check that if 2.4 ghz is just as bad for signal quality.