I don’t have a main router. My GL-MT300A included in the Internet directly.

/etc/config/wireless

config wifi-device ‘radio0’
option type ‘mac80211’
option path ‘10180000.wmac’
option htmode ‘HT20’
option hwmode ‘11ng’
option txpower ‘20’
option channel ‘auto’
option disabled ‘0’

config wifi-iface
option device ‘radio0’
option network ‘lan’
option mode ‘ap’
option ifname ‘wlan0’
option wds ‘1’
option ssid ‘MYAP’
option encryption ‘psk2’
option key ‘Urt…7’
option disabled ‘0’