LB1120 Setup

I have an LB1120 4g modem that I want to connect directly to an existing router (replacing the existing DSL modem) in order to provide 4g service to my home wifi network.  It will be using an AT&T SIM card/data plan.

 

Does the modem need to be set to router mode or bridge mode?

Is there anything that I need to change in the modem's configuration? 

 

Thanks...