WiFi legacy incompatibility

[alfonder]

A WiFi scale (probably ESP32 based) uses 2.4 GHz to sync.

The problem is: the device connects successfully to the old Keenetic Ultra2, but can't connect to the modern Keenetic Challenger SE (KN-3911) with the same WiFi settings.

ku_rd config fragment:

interface WifiMaster0
    country-code DE
    compatibility BGN
    rekey-interval 86400
    up
!
interface WifiMaster0/AccessPoint0
    rename AccessPoint
    description "Wi-Fi access point"
    dyndns nobind
    mac access-list type none
    wps
    authentication wpa-psk ns3 xxxxx
    encryption enable
    encryption wpa2
    ip dhcp client dns-routes
    ip name-servers
    ssid Deutschland25
    wmm
    rrm
    up
!
interface WifiMaster0/AccessPoint1
    rename GuestWiFi
    dyndns nobind
    mac access-list type none
    authentication wpa-psk ns3 xxxxxx
    encryption enable
    encryption wpa2
    ip dhcp client dns-routes
    ip name-servers
    ssid Umbreon
    rrm
    up
!

KN-3911 config fragment:

interface WifiMaster0
    country-code DE
    compatibility BGN+AX
    channel width 40-below
    tx-burst
    rekey-interval 86400
    beamforming explicit
    atf inbound
    vht
    downlink-mumimo
    uplink-mumimo
    spatial-reuse
    up
!
interface WifiMaster0/AccessPoint0
    rename AccessPoint
    description "Wi-Fi access point"
    mac access-list type none
    wps
    wps no auto-self-pin
    authentication wpa-psk ns3 xxxxx
    encryption enable
    encryption wpa2
    ip dhcp client dns-routes
    ssid Deutschland25
    wmm
    rrm
    up
!
interface WifiMaster0/AccessPoint1
    rename GuestWiFi
    mac access-list type none
    authentication wpa-psk ns3 xxxxxx
    encryption enable
    encryption wpa2
    ip dhcp client dns-routes
    ssid Umbreon
    rrm
    up
!

It looks like some new features are incompatible with old legacy wifi clients.

During non-successful attempts there are the next entries-set in the log:

[I] Apr 21 23:18:28 ndm: Network::Interface::Mtk::WifiMonitor: "WifiMaster0/AccessPoint1": STA(d0:49:00:2f:c1:91) had associated. 
[I] Apr 21 23:18:28 ndm: Network::Interface::Mtk::WifiMonitor: "WifiMaster0/AccessPoint1": STA(d0:49:00:2f:c1:91) MIC differs in key handshaking (msg 2 of 4-way). 
[I] Apr 21 23:18:32 ndm: Core::Syslog: last message repeated 4 times.
[I] Apr 21 23:18:33 ndm: Network::Interface::Mtk::WifiMonitor: "WifiMaster0/AccessPoint1": STA(d0:49:00:2f:c1:91) had deauthenticated by AP (reason: previous auth no longer valid). 

Can anyone suggest which setting add/remove to achieve compatibility?

Edited April 21 by alfonder

[alfonder]

Additionally, here is the log from ku_rd on successful connection of the scale:

[I] Apr 25 00:46:52 ndm: Network::Interface::Mtk::WifiMonitor: "WifiMaster0/AccessPoint1": STA(d0:49:00:2f:c1:91) had associated. 
[I] Apr 25 00:46:52 ndm: Network::Interface::Mtk::WifiMonitor: "WifiMaster0/AccessPoint1": STA(d0:49:00:2f:c1:91) set key done in WPA2/WPA2PSK.