@Ebola 

Hi, thanks for posting question on our community~

We may need to confirm more information to understand your situation better.

1. What device did you connect to the USB port? Do you mean the read-write speed is slow?

If so, there is many factors that influence the read-write speeds, so it is not easy to find out the problem. There is a simple way to see if the speed is normal: If you are using a USB drive or hard disk, please plug the same USB drive or the hard disk to the same USB port on the computer (if it is a USB2.0 on the modem router, please use USB2.0 on the computer as well), then transfer a same file and compare the speed with it on the modem router, please take screenshot of the speed result and share us.

2. OneMesh only works between a OneMesh router/modem router and OneMesh Wi-Fi Extenders/Powerlines. But Archer AX73 is a wireless router, which does not support range extender mode, either. Archer AX73 supports wireless router mode and access point mode. 

3. Moving on to the second point, can your share your network topology? Did you set AX73 as AP mode? As parental control works basis on device's MAC address. If random MAC is enabled, which may influence the performance of parental control.