I upgraded using 'oupgrade -l' on 30/09/2018 and unable to connect WiFi following above steps by an.arshadali. Below is the result:
root@Omega-4D3D:~# cat /etc/config/wireless
config wifi-device 'radio0'
option type 'ralink'
option variant 'mt7628'
option country 'US'
option hwmode '11g'
option htmode 'HT40'
option channel 'auto'
option disabled '0'
option device_mode 'apsta'
option op_mode 'preference'
config wifi-iface 'ap'
option device 'radio0'
option mode 'ap'
option network 'wlan'
option ifname 'ra0'
option encryption 'psk2'
option key '12345678'
option disabled '0'
option ssid 'Omega-****'
config wifi-iface 'sta'
option device 'radio0'
option mode 'sta'
option ifname 'apcli0'
option encryption 'psk2'
option network 'wwan'
option disabled '0'
option key 'MyPassword'
option ssid 'MySSID'
config wifi-config
option key 'MyPassword'
option ssid 'MySSID'
option encryption 'psk2'