I have an Ubuntu server acting as a gateway for inbound internet connections. This server shut down unexpectedly because of overheating and lost all internet connections during business hours. How can I implement a fail-over on a back-up server that I have, meaning that if the gateway shuts down, the two ISPs that I have go directly to this back-up server with as little downtime as possible? The back-up server has the same configuration and hardware as the gateway.
Thank you in advance!