It doesnt look like that router has support for Luci to read the wifi information.
The stand out thing to me is your main router is saying the ‘actual datarate’ is 10Mbit/1Mbit.
I don’t own this router - but maybe if you ssh into it and run =iwinfo= you’ll get output like this
root@GL-AR300M:~# iwinfo
wlan-sta ESSID: “blah”
Access Point: blah
Mode: Client Channel: 7 (2.442 GHz)
Tx-Power: 20 dBm Link Quality: 51/70
Signal: -59 dBm Noise: -95 dBm
Bit Rate: 121.5 MBit/s
Encryption: WPA2 PSK (CCMP)
Type: nl80211 HW Mode(s): 802.11bgn
Hardware: unknown [Generic MAC80211]
TX power offset: unknown
Frequency offset: unknown
Supports VAPs: yes PHY name: phy0
wlan0 ESSID: “gl-inet”
Access Point: blah
Mode: Master Channel: 7 (2.442 GHz)
Tx-Power: 20 dBm Link Quality: 70/70
Signal: -34 dBm Noise: -95 dBm
Bit Rate: 94.8 MBit/s
Encryption: WPA2 PSK (CCMP)
Type: nl80211 HW Mode(s): 802.11bgn
Hardware: unknown [Generic MAC80211]
TX power offset: unknown
Frequency offset: unknown
Supports VAPs: yes PHY name: phy0