Hello, please read the following information
1. Configure parameters of a WAN port.

2. Click the WLAN tab, and choose 2.4G Basic Network Settings from the navigation tree on the left. In the right pane, configure the basic parameters of the 2.4G Wi-Fi network.
Figure 1 2.4G basic network settings

3. Click Apply.
Note:
If three SSIDs are activated, they are displayed in the SSID list. When you select which one, you can set the parameter.
If the problem persists, refresh the web page.
If the problem still cannot be solved after refreshing the page, restart the device.
If the problem still exists after restarting the device, the device may be a customized version provided by the carrier. Some functions have been deleted. You need to contact your local carrier or device provider to obtain technical support.
Good luck! My friend