"permanent fix was to shorten the backhaul WiFi password by 1 character." You mean after a auto update , just remove one character of the backhaul wifi password or A change the whole password did the trick?
Asus is not responding on any problems regarding ZenWiFi and connect problems like dropping connection, randoms restarts, backhall switching back to 2.4ghz, etcsearch for all issues with concerns these descriptions zero asus comments.
