NanoHD Wifi Slowing down my speeds

Hello, I’m Finishing an Install on a friends network, I went with a USG, US 24 port poe switch and a UAP NanoHD, Now so far so good, only hiccup was that cloud access was not working but after removing it and re enabling it all was good. but after installating all, my friend did a speed test, and connected his connection was spot on, 400 mb in his case, but when he got on the wifi it dropped to half that or lower. What can this be the case and how can I fix this?

What are the capabilities of the Wireless in the device used?

NanoHD’s are rated for 300 Mbps @ 2.4 GHz, and 1733 Mbps @ 5.0 GHz. Can you confirm that the device testing the speed is connected at 5.0GHz, in good enough range, and that the speedtest is conducted on a close server? (Testing on a hard wired connection first to ensure wireline speeds are up to spec)

Wired connection was tested both on the switch and direct to the modem, and both times over 400 mbps, when connected over 5gz it dropped to 200 or so mbps, tested in front of the AP, 2 times on different location around the house.

I’m having the same issue. Did you manage to fix this?