We have multiple internet links with distinct ISPs connected to a single firewall/router. It may happen that one of our links goes down and we won't notice it because of automatic fail-over to WAN link B. Once the secondary (B) connection goes down we'll then notice that both are down because there's no other fail-over option left.
Can PRTG assist on monitoring fail-over links to warn me when one of them is down even when we still have connectivity from the other link? How can I setup such as multiple internet links monitoring?