Surf OTG, USB modem and Bridge Mode

Can someone tell me if the Surf OTG supports passing the external IP address received from a USB modem to an internal device on the LAN?

I assume I would be using the bridge mode functionality in the device, but it seems to disable the USB modem support when I enable it.

Also, is there another product that would support this functionality? I am looking to pass a static IP address from a cellular provider to a firewall behind the Surf OTG.

The Surf OTG does not support IP passthrough mode but this option is available on the BR1 with the embedded modem.