I've been using the wan balancer for a few months now.
About a month ago, untangle stopped working. I suspect it was because of an automatic update, as no-one made any changes to the server close to the incident. The virtual machine failed to start up.
I entered recovery mode and reloaded a backed-up configuration from the hard drive (2 days old) and the system started again.
However, the wan balancer stopped working.
Previously it was balancing 2 wan connections perfectly.
Whenever I now switch on the wan balancer, all client connectivity drops. Current connections are kept alive, but no new connections are successful.
If I switch off the wan balancer, connections work again - but only over the one wan connection.
I have removed and re-installed the wan balancer & wan failover "devices" but still get the same problem.