TP-Link WR902AC V1 slow on 5GHz

Since using release 18.06.0 on my WR902AC I recognised only a bitrate of 6MBit/s. With 2.4GHz I get more than 60 MBit/s. I'm not 100% sure, but I think it was better with a snapshot of LEDE 17.xx.
Is there something I could do?

Kind regards

That is a firmware limitation of ath10k devices, which handle the rate adaption algorithm in firmware and don't report the current rate back to the kernel, rendering this value meaningless (the actual rate is higher, you just won't get to see it). Do a real speed test (LAN to WLAN) and/ or check what your clients report about the current wireless rates.

Thanks for your answer. The point is, that I have not only a problem with the display of the bitrate, but also with the streaming of videos over the 5GHz network. That's, why I looked for the bitrate on the router. And now I look for the reason.