1% of requests get connect exception and are not sent

I have a shared worker pool that I'm using for all my producers. I have a server that sends requests to a single domain - using camel netty4-http

when running a small load test, no more than 20 requests per sec, I see that some of the requests (about 1%) are timed out and then the netty producer sends a ConnectException: (code snipped from NettyProducer class

if (!channelFuture.isDone() || !channelFuture.isSuccess()) {
ConnectException cause = new ConnectException("Cannot connect to " + configuration.getAddress());
I did a tcp dump and saw that the requests that were timed out were never sent from the server - there was no TCP request that was made.

the request is simply not sent and there is no indication as to why or what is the problem - except a timeout on something that causes the ConnectException to appear

I don't know if it is related, but I'm sending the requests using a routing slip