Thanks Jerry. Here is the content of my /etc/config/wireless:

config wifi-device ‘mt7628’
option type ‘mt7628’
option htmode ‘HT40’
option ht_txstream ‘2’
option ht_rxstream ‘2’
option hwmode ‘11g’
option noscan ‘0’
option txpower ‘20’
option txpower_max ‘20’
option country ‘US’
option region ‘0’
option band ‘2G’
option mimops ‘3’
option wmm ‘1’
option channel ‘1’

config wifi-iface
option device ‘mt7628’
option network ‘lan’
option mode ‘ap’
option encryption ‘psk2’
option ssid ‘GL-MT300N-V2-401’
option wds ‘1’
option disassoc_low_ack ‘0’
option ifname ‘ra0’
option key ‘Animal12’

config wifi-iface ‘guest2g’
option device ‘mt7628’
option network ‘guest’
option mode ‘ap’
option wds ‘1’
option ssid ‘GL-MT300N-V2-401-Guest’
option encryption ‘psk2’
option key ‘goodlife’
option ifname ‘ra1’
option disabled ‘1’
option guest ‘1’
option disassoc_low_ack ‘0’

config wifi-iface ‘sta’
option device ‘mt7628’
option network ‘wwan’
option mode ‘sta’
option ifname ‘apcli0’
option ssid ‘DLF_Power’
option channel ‘1’
option encryption ‘psk’
option key ‘THE KEY OF MY NETWORK’
option disabled ‘1’

Is there a problem with one of these parameters ?
Why is this last network “disabled” ?

Thank you again.
Joël.