@jmxjmx2 

Hey, I used to have Archer VR1600V and the USB writing speed is almost 5MB/s(40mb/s);

And the support told me it was normal.

@Lawrence-C Oooooh, I see. Then those 13 MB/s seems that I am the lucky one. That's bad. That's really bad. I mean bad for TP-Link as people will stop to trust their products and specifications of their products at all.To have a regular  USB 3.0 port with 13 MB/s or lower  speed that is ridiculous.