Much weaker 5GHz radio signal on ath9 compared to ar71xx on wndr3700v1

Much weaker 5GHz radio signal on ath9 compared to ar71xx on wndr3700v1
I used exactly the same WiFi channel settings with a max power (region USA).

With Android wifi analyzer I measured at the same distance (about 7 meters) the wifi signal strength.
ar71xx build showed -42 dBm
ath79 build showed -68 dBm
This happened on different channel numbers.

I sticked at ar71xx build as both bands 2.4GHz and 5Ghz have a strong signal.
Ofcourse later I might decided to move to ath79 once this is solved

Did somebody experienced / tried this as well?

Solved in OPENWRT_19.07.4-ath79. Excellent wifi signal strenght in 2.4Ghz and 5Ghz.
Thanks all other functions like Wireguard, OpenVPN, Adblock, DynamicDNS, Wifi Schedule, Wake on LAN, Netwrok Shares, SQM QoS, LED configuration, BandWith Monitor and uHTTPd work perfect!

Many Thanks to all volunteers working on OpenWRT. what a perfect piece of open source sofware with high quality.