Dual-WAN Gateway issues

  • Dears,

    I've got a dual WAN setup running for a while now. Both links are capable of 200/12 mbit/s and have the same ISP. Until yesterday everything was working as expected, although one modem was acting as a NAT router just providing an interal ipv4 address. There are problems like double NAT etc but the most anoying was that DS-Lite was used. I need an ipv4 address in order to let another pfsense box connect via openvpn in case the first WAN goes down. Therefore, I managed to set the second modem into bridge mode, too (the other one was already), providing just the modem functions and giving me an ipv4 address.

    What I realise now is that I have serious packet loss on both WAN interfaces. If I sum up the percentages I will end up at about 100%. If I force one interface down the packet loss will be zero on the other one. I investigated a bit further and saw that the two WAN interfaces got gateways with different IPs but with the same MAC.

    My questions are:
    The same MAC being present on the two different gateways is causing the packet loss. Is this correct?
    Is there anything I can do to prevent this?

    Thanks for your help

  • Changed the switch and the problem is gone.

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