Hello, friend!
The display ont wlan-info command can be executed on the OLT to query the SSID of an ONU, but the SSID of the ONU cannot be modified.
Generally, the SSID of an ONU is configured and modified by logging in to the ONU web page.
Choose Settings > Wireless Network. In the navigation tree on the left, choose 2.4G Wireless Basic Configuration. In the right pane, set the basic parameters of the 2.4G wireless network.
You can also remotely change the SSID and password of an ONU through the NMS (U2000, NCE).
Thanks!