Adding second ISP causes problems
With only 1 WAN connection to the internet, everything works fine including a web server behind the firewall. We are using NAT.
When I add a second WAN connection to a different ISP and add a second default route for that interface, traffic to the web server from outside no longer works. Both static routes have the same distance and priority.
I don't understand what is going wrong or how to fix it. Does this occur because traffic come in from one ISP and is going out to the other? Do I need to use a policy based route?
I've watched the videos on redundant internet connections, but am not currently interested in load balancing. The original WAN connection is slower and so may someday want to set up a WAN status check and failover.