@Rasmus_o 

Hi,

I assume you are talking about Megabytes per second.

If so, then I would say 50 MB/s of write performance (i.e. copy data from the PC to the USB HDD attached to the AX73) can already be considered as quite fast for a router of this price. 

In general, USB transfer speeds of routers are highly CPU dependent and for speeds greater than 100 MB/s you will need a CPU that is likely only to be found in somewhat more expensive routers.

Btw, what kind of read performance do you get from your setup? TP-Link routers tend to achieve substantially higher read speed from their USB port than what their write speed is.