@BlueSugar 

Hi,

The are many possible reasons for low speed.

As for the data throughput via LAN cable.

A good starting point for troubleshooting would be to perform a Factory Default Restore on the AX50 and after it has re-booted do a speedtest right away. (If your case requires a special configuration of the AX50's Internet connection (like PPPoE) then configure it accordingly, but don't adjust any more settings yet and don't log into TP-Link cloud)

If after the Factory Default Restore the speed over LAN cable is still low, then check that your Ethernet cables are okay or, if you have some lying around, replace them for a test.

If after the Factory Default Restore the speed over LAN cable goes up to 900-1000 Mbps, then you can continue to configure the AX50 as you'd like, but I recommend you perform another speedtest after each setting you change, so that if the speed drops down again you will know which setting caused the speed to drop.

As for the data throughput via Wi-Fi.

Same as above, but you will also have to consider the technical specifications of your Wi-Fi hardware. You will probably need a fairly high end smartphone or a computer with an Intel AX... Wi-Fi card to achieve 900-1000 Mbps over Wi-Fi.