After i do "uci set wireless.@wifi-device[0].disabled=0", my wireless router's SSID disappear

Dear OpenWRT peers,
I have a TP-link R720N wireless router and I've installed OpenWRT on it. It work properly until I was planning to try to connect the R720N to my mobile phone which is my main internet access provider.
I followed an webpage with title of: Connect to client wifi network. (viewed on 21 April 2019 https://openwrt.org/docs/guide-user/network/wifi/connect_client_wifi) when followed the webpage instruction to a command line operation, quote,
"uci set wireless.@wifi-device[0].disabled=0
uci commit wireless
wifi "

when i finished above command line and enter it a while, SSH back stopped work. Meanwhile, the browser based Luci bash feedback "it works". then I can not find my R720N''s SSID even through I hard rest my R720N and re powered it again.

would anybody please to help me to get my R720N wireless router ( @openwrt) SSID back again?
Thank you in advance.

Vincent