apologies if this is really a newbie question but I'm not quite sure where to begin and am hoping someone might give me a clue or two
our office router is load sharing 3 dsl lines to one lan and has been going a great job of it
however, when I look at the logs I see a lot of entries that seem to be ip broadcast or multicast that appear not to have a route? It appears to always be UDP

any chance of a little enlightenment about where to look? What have I broken?

As far as I know that traffic is DropBox LanSync

thanks mrz

interesting. we've stopped using dropbox in the office so there should not really be much left ? (although perhaps the odd device or two with personal stuff)
even when we used to have more dropbox i don;t recall us getting these messages in the logs

is there a general rule about what "out unknown" means and what to look for? seems surprising to me that the router does not know what to do with an IP broadcast and that it logs it... I'm guessing we might have done something incorrectly in our config... or left something out?

is this normal behavior in the log ? (it makes it very hard to see anything else as there are a lot of them)

also,at least one of those machines is definitely not running dropbox (raspberry pi with traffic on udp port 7?)

You will always see "unknown" out interface for traffic that is not going to be forwarded over the router, because there is simply no out interface.
dropbox is UDP 17500, other ports are for different protocols. Just drop all unknown traffic in input chain and leave only that you will be using for management.

thanks.
upon deeper inspection i found that someone (other than me had inserted a firewall rule on the input chain to log everything... which seemingly caused these messages to show up each time the input chain saw a packet that it had no route for.
all better now... and I've learned a few things