Hello

When i bought my Archer T4E my PC didnt recognized my 5G wifi, i reinstalled drivers a couple of times. Nothing.
Today when i started to mess up with router configuration i made my PC recognize the wifi. Theres problem.
On 2.4ghz i have 2Mbps wifi when on phone in my room it is about 50Mbps, on 5G its 11Mbps when phone has 70Mbps
Why? Can i do sth about it? 

Thanks for help!