One of our ISP's has given us a second internet connection. Eventually the existing connection will go away. For testing, they assigned the new service the same /24 as the existing connection. They assigned an address from that block to the customer interface on their new router (we confirmed the address was available).
I connected the new router to a spare port on my UTM and assigned it the same subnet as the existing connection. I did not yet set a default gw. When I enable that interface, the UTM stops routing external traffic completely. Apparently having two interfaces with the same subnet (although physically separate) confuses it?
Is there a way I get the UTM to recognize this new WAN before disconnecting the existing one?
This thread was automatically locked due to age.