Only 54 MBit/s on TP-Link CPE510 instead of 300 MBit/s

I also can confirm this, CPE 510 V3.20, latest snapshot build, 54 Mbit is definitely the maximum for this device even if I see RX/TX rate 300/300. I get higher speeds with stock firmware but the link is not stable and I can use only DFS channels. I can't say that the device is complete garbage, it is a very stable connection with OpenWrt, the device is definitely usable, but the speed is far from satisfactory.