wr44 failover connection

I need help to change the configuration of a Digi Transport WR44.
We have a WR44H-XXX-F00 that is connected via cellular “always on” (on PPP1) and connected to an internal Lan on port ETH0 (range 10.4..). Dhcp is enabled ( to 120) and PPTP on PPP5 is enabled (as described in QN_011).

Now we activated a satellite internet service and they gave us just an ethernet cable with a fixed IP address to be used by lan clients as a gateway.
I plugged this cable into the ETH2 port.

I need suggestions on how to configure the ethernet port ETH2, the WR44 to route the internet traffic to the satellite connection and use the cellular line as a backup.
Moreover I want to connect via VPN when the satellite link is up using the fixed IP instead of the dynamic ip acually used when connected via cellular connection (when satellite is up, cellular link should be disconncted).
Is it possible?

Thanks in advance for your help,


Please refer to the application note.