My solution utilizes IP passthru. To improve security, I have worked with Verizon and established a private Cell network. The PPP interface of the digi modem receives a private address.
With IP passthru enabled, the device attached to Ethernet 0 receives the proper IP from PPP 1. However, traffic is not forwarded to the device. ICMP and all other traffic appears to terminate at the Digi.
Thank you for the informative response. Initially, I tested with the analyzer and confirmed that return traffic stopped at the Digi.
I then put a new SIM in the Digi that was on Verizon’s public network and confirmed passthru worked as expected. I then put the SIM that is on my Private cell network back in the Digi and now passthru is functional. I’m not certain why this is, but I’ll take it.