I have a TL-WPA8631P Kit, with TL-PA8010P connected to Draytek 2865Lac router, and TL-WPA8631P v.3.0 at far end (approx 15m away) of old stone-built house. Draytek router is using EE 4G connection via external antenna. All speed tests below done via web browser at speedtest.net, using same Windows laptop and cables, and repeated at least 6 times each.

1. Ethernet cable to router - 68Mbps download, 28Mbps upload.

2. Wi-fi to Draytek router (using 5Ghz band) - 35Mbps download, 20Mbps upload.

3. Ethernet cable to TL-WPA8631P - 65Mbps download, 25Mbps upload  

4. 5Ghz wi-fi (with 2.4Ghz turned off) to TL-WPA8631P - 8Mbps download, 16Mbps upload

5. 2.4Ghz wi-fi (with 5Ghz turned off) to TL-WPA8631P - 4Mbps download, 14Mbps upload

Things tried so far:- upgraded TL-WPA8631P firmware to latest version (V3_220330) - no difference. Moved TL-WPA8631P to different sockets around the house - no change. Tried different wi-fi mode settings - no change. Have a second TL-WPA8631P unit which tests out exactly the same, suggesting there's a fundamental problem with the wi-fi on these units.
Has anyone had better wi-fi download speeds from these units? If so, what did you do?
Thanks.