I'm with my rt-n56u on 17.01.4, r3560. When I disable 5Ghz wifi with Luci (or wifi down cmd) I cannot reactive it in Luci (or wifi up cmd). To be exact: According to Luci the interface is up, but I cant see the SSID with my mobiles. I have to reboot the router to get 5GHz back.
My wireless config:
config wifi-device 'radio0' option type 'mac80211' option hwmode '11g' option path 'pci0000:00/0000:00:01.0/0000:01:00.0' option channel '3' option htmode 'HT40' option country 'DE' option txpower '20' #option noscan '1' config wifi-iface option device 'radio0' option network 'lan' option mode 'ap' option ssid '2G' option encryption 'psk2' option key 'mykey1' config wifi-device 'radio1' option type 'mac80211' option hwmode '11na' option path '10180000.wmac' #option htmode 'HT20' option channel 'auto' option country 'DE' option txpower '20' option noscan '1' option log_level '0' config wifi-iface option device 'radio1' option network 'lan' option mode 'ap' option encryption 'psk2' option key 'mykey2' option ssid '5G'
Also curious: The 5G option htmode 'HT20' has to be commented out and the channel to be 'auto'. If try to define a fixed a channel 5GHz doesn't start (even after reboot) at all.
I know there are some other post here where problems w/ 5GHz are reported. This might be the next.