WAN1&WAN2 -- modem--DSL line--fixed IP in eth encap
WAN3&WAN4 -- modem--DSL line--fixed IP PPPoe

1&2 is one broadband vendor and 3&4 another.

It's have been 2 months. all the WAN port will be disconnected now and then.

put a brandnew modem on WAN3, just the same. Upgrade the 3300V firmware and modem firmware as well, still the same.

the only way to keep WAN stable is to exclude it from load balance which means no traffic over this line.

But the traffic is not so high at all, only up to 50million packets for each WAN line one week.

Anyone got same problem?