I don't know why. If I'm setup AX86U as main router (official/merlin firmware) and 2 zenwifi XT8, only official latest firmware 25790 only will give 5Ghz both connected. If using any RC firmware to both zenwifi. only one of them will be 5Ghz. The other one only stuck at 2.4Ghz.
View attachment 28955
AX86U as main router (official/merlin firmware/RC Beta)
Zenwifi as node (RC any firmware inluding latest 41535 )
View attachment 28958
AX86U as main router (official/merlin firmware/RC Beta)
Zenwifi as node (Official 386.25790)
so for now, I just use official 25790 for XT8 and can't use bind features.