.b292 didn't gave me any errors, but when testing iperf3 speed in a location separated by 2 walls from router, it always gives less speed than the correct calibrated BDF used in snapshot. Even if .b292 uses higher or the same Tx power.
Near the router there was no difference I could see. (~1.5Gbits)
Far from the router, behind 2 walls, .b292=~700 to 800Mbits, snapshot default BDF=~850 to 980Mbits.
So I'm back to the default BDF with the correct calibration.
Will wait for a Tx power fix.
One thing I notice is that WRX36 has dual-band antennas and ax3600 has single band antennas. Don't know if there's any difference when setting/reading Tx power becuse of this.