Half connection is dropped between F5 BigIP and Openstack

Hi everyone!

I have some curious situation.  Created for testing purpose Virtual Server on my BigIP VE which worked good with requests from internet. As my company has cloud based on OpenStack , I've made test client on OpenStack too. 

To my suprise more or less half of the requests started to time out. 

I know that it is to less information to give diagnosis but maybe somebody had similiar problem with traffic beetwen BigIP nad Openstack?

Regards