Yes, this is possible with many Peplink routers.
At Peplink, this function is called "Wi-Fi WAN".
You can find out whether it is possible with your model in the respective data sheet or please contact us.

If available, you will find this function in the configuration interface of the router under:
Network --> WAN --> Details

WAN Connection Name
You can name the WAN connection accordingly here

Operating Schedule
You can define a time control using the drop-down menu.

Independent from Backup WANs
If this checkbox is activated, this WAN connection works independently of other backup WAN connections.

Standby state
This selection specifies the standby behavior of the WAN connection. "Remain Connected", also known as "hot standby" or "Disconnect" (cold standby).
Remain Connected shortens the activation time if required, as the line is permanently connected and does not have to connect first.

MTU
This setting defines the maximum (data) packet size. The default value is 1440. We have had a very good experience with "Auto". Here the router attempts to determine the MTU independently.
The MTU must match your connection. For DSL connections it is usually set to 1492 and for cable connections to 1500. The values for LTE vary from provider to provider.