Drop-in for ISP migration


I have an older triple balance model and I was wondering if it was possible to use it to help in the process of Migrating ISPs. Both of the ISPs provide firewalls and currently they are both configured with their LAN ports on our internal network (on different IPs). I was wondering if through a combination of drop in mode and manual configuration of the second WAN port it would be possible to configure this device to act as a transparent three legged router.

Both of the firewalls have a complex battery of rules and it would require a good bit of work to shift their internal IP off of the same subnet. basically internally we use 192.168.50.x / and one firewall is at and the other at What I would like to do is set the Manga up in drop-in mode where WAN1 connects to the first firewall and WAN2 to the other and the LAN port connects to the LAN. To do this I would need the Manga to have all three of the active ports configured on the same subnet and basically do connection tracking and route traffic to its originating port.

Is there a way to configure something like this ? ( I suspect not, but I wanted to ask to be certain )

Drop-in Mode is a feature that is available with Peplink Balance model 210 and above. Drop-in mode can be configured on any WAN port. But there is only one WAN port can be configured in Drop-in mode. Thus it might not be an option for the migration approach.

If you can provide us the detailed network diagram, we can try to propose some ways to do it here.