Netgear ex3800 connection limit

I’m using my Netgear extender to connect my PC to the internet as I can’t use a cable. My problem is that the extended reduces the speed from 280 mbps to 90 mbps. The extended is only 2 meters away from the modem and they are in the same room. I also get feedback that the connection is very good between them.

In the manual is says that the extender can deliver 750 mbps, which is no where close to what I am getting. Can anybody help me with this issue?