I've been using mode 4 with four slaves, however looking at ifconfig showed that the traffic was not balanced correctly between the interfaces, the outgoing traffic has been alot higher on the last slave.
It does have the lowest Rx, it just likes to talk? Maybe the talk suppresses others on the collision domain, so it appears to be the fastest way out, which makes more talk, suppression. Some systems are naturally unstable in subtle ways.
Nothng extra running on, or pointing to, that slave? Is that IP in the DNS? Maybe some sample snooping will show if there is something special about that huge send traffic. Snapping the stats a frequet intervas to a flat file would allow you to see when there is some special activity, like a net backup.
