A router that does this and support either from your company IT or the router maker. This failover is not in any known consumer grade router. You find yourself getting into Cisco commercial gear. That is, figure a few grand when done.
There are 2 buildings. Building A has ISP is AT&T, Building B has ISP is Spectrum. These buildings are connected to each other by VPN.
I want to use AT&T from building A become a backup internet for building B by using failover function, and also Spectrum will become a backup internet for building A. But dual wan router requires these ISPs must be in the same building. Is there any way to do it?