2 interfaces, same ISP, same gateway IP, monitoring gets confused

  • I have 2 WAN links into the same ISP. Periodically, the links will get the same gateway IP. Their external static IPs are consistent and different. It is just their gateway IPs that are sometimes the same. This causes me grief with gateway monitoring. When automatically assigned monitoring IP addresses are the same pfSense doesn't get reliable pings from each interface so the gateways remain in 'Gathering data' state. I have manually set monitoring IP addresses to get around this. But I don't think that will solve it.

    I've just discovered the following log entry:
    php: /system_gateways.php: Removing static route for monitor n.n.n.n and adding a new route through g.g.g.g

    g.g.g.g is the gateway address. Now because I have 2 links from the one ISP I am likely to get the same gateway address some of the time. If my monitor IP address is to be routed through the gateway address then I will not know if one of the links is down because the other link will have the same gateway. Is my thinking correct and should monitoring IPs be routed through the actual pfSense gateway (or interface IP) rather the ISP assigned gateway?

    I use multi-WAN for load distribution and control. Failover is only used in one direction so being able to detect individual links being down is important.

    Thanks, Greg.

  • @Reiner030:


    normally the monitor ip could be gateway IP of your WAN interface…
    If both WAN interfaces have same gateway then you should "randomly" use external IPs to get a monitoring up.
    As written in other threads the pfSense would set special routes for this monitoring IP to use only WAN1, WAN2,...WANn to this special IP.

    So you need to use an "always up" IP to guarantee monitoring is working.
    GoogleDNS could be offer IPs...,
    OpenDNS could also help:,
    or you use 2 different IPs of your provider...