As it turns out (viewtopic.php?t=203117#p1046670), wifi-qcom(-ac) drivers always enable 802.11b on 2.4 GHz interfaces: Basic rates are set to "1, 2, 5.5, 11" so beacons are sent at a mere 1 Mbps.
I realize that making basic rates completely customizable with the new wifi drivers might be an issue, but please provide at least an option to set the 2 GHz interface to 802.11g+ with basic rates "6, 12, 24" like already used on 5 GHz.
When fast 5 GHz is available, slow speed on 2 GHz is less of an issue. But if available airtime on 2 GHz can be improved easily, I think it should be done. Especially when there are new 2 GHz only devices like hAP ax lite.
Thank you.