I recently set up a multi-wan connection for a small company, because they are at the end of the line for any possible ISP, services do go down, and they really depend on their Internet connection. I am using a CISCO RV042, which can work in either failover or in load balancing mode. It seems logical to use load-balancing - as long as you have two connections, why not use them. However, load-balancing leads to the problem I am about to describe.

A surprising number of web services apparently establish multiple TCP connections, and then fail when those connections come from different IP addresses (as they do, when load-balanced over multiple WAN interfaces). Most recently, the new eBanking interface from this company's bank apparently does so. In the case of the eBanking connection, for example, it simply becomes impossible to log into the service. Other services deliver weird errors, or just don't work properly.

  • I can correct this by binding each individual PC in the RV042 to a single WAN interface. However, this means using static IP addresses instead of DHCP, so this is not a good solution.

  • I can correct this by running the RV042 in failover mode, so that only a single WAN is in use at any given time. Also not ideal, since the other connection goes essentially unused.

  • Of course, one can also report the problems to the various web services. Good luck with that.

There are lots of companies with multi-wan connections. Surely there is a better solution? Anybody?


It's not possible without connection tracking. Basically router must be able to:

  1. track incoming and outgoing connections
  2. mark them
  3. direct through different routing tables based on connection mark.

Check if your router supports this. If not and you really want to load balance traffic), you can replace it Mikrotik routers (almost any model will do). It's relatively easy to setup load balancing on them (see Firewall marking on Wiki)

Also Mikrotik have PC version (with 24 hour trial) so you can test if it will work for your setup.

PS. It's not actually problem of web services. TCP connection in most cases identified by source and destination ip and source and destination port - so when ip changes, it's considered different tcp session.

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