My brand new adapter doesn't go faster than 40 Mbps on my 240Mbps 5ghz internet. My PC sits less than 3 meters away from the router and when I connect the adapter on my laptop it goes to 90 Mbps without any driver install... I'm currently using Windows 10 Home 64 bit and tried literally everything, reinstalled the driver, tried the Windows 8 driver, changed the USB port (only have USB 3.0 and 3.1 on my system), changed the frequency, port and wavelength on my router, disabled the onboard LAN card, changed the Wi-fi mode on the adapter settings, nothing worked!!!

I'm starting to think the issue has to do with the compatibility between my mobo and the adapter, it is a 450M from Asus.

Do you have any suggestion what the problem may be?