Hi Dave,
I see HF#24 include a fix to a collectors disconnection issue, I suggest you to apply latest 10.5.1HF#35
Regarding the MessageQueueSize I don't think we have a supportabiltiy metric for this, maybe you just need to adjust the active client connection: transport.override.isengard.high.concurrency.pool.max.size, I am afraid, this is a tuning exercise you need to perform in your environment, the values are different for on each environment.
Try setting the values to outgoingMessageQueueSize=16000 and pool.min & max to 15, but if the problem persists, open a support case.
Capacity Planning and Server Deployment Options - CA Application Performance Management - 10.5 - CA Technologies Documen…
Regards,
Sergio