Archer C2 V1 - 5Ghz port not connecting to switch

(I have searched the forum but could not find someone with the same problem, so openning a new thread)

everything works on my router using OpenWrt 22.03.0 r19685-512e76967f / LuCI openwrt-22.03 branch git-22.335.71542-7e42425.

I configured WiFi and the the 2.4Ghz band works OK. The 5Ghz band, same configuration, "works" as in stations can authenticate and connect but are not getting switched to the LAN interface. Tested also with the default OpenWRT network - same problem!

Has anyone encountered such problem before?

Here is the part of /etc/config/wireless

config wifi-device 'radio0'
#       option type 'mac80211'
        option type 'rai0'
        option vendor 'ralink'
        option path 'pci0000:00/0000:00:00.0/0000:01:00.0'
        option channel '36'
        option band '5g'
        option htmode 'VHT80'
#       option cell_density '0'

config wifi-iface 'default_radio0'
        option device 'radio0'
        option network 'lan'
        option mode 'ap'
        option encryption 'none'
        option ssid 'OpenWrt-5'