Just for the record, we found the issue. There was some filtering being applied in the bridge code which randomly (?) dropped some DNS requests. Setting: net.bridge.bridge-nf-call-arptables = 0 net.bridge.bridge-nf-call-iptables = 0 net.bridge.bridge-nf-call-ip6tables = 0 completely resolved the problem. I've written up full details here: http://buriedlede.blogspot.com/2012/07/debugging-networking-problems-with.html -nld