Load balancing issues

Hi,

That's the default cookie persistence profile. Did you try to disable source address persistence as a fallback persistence and left only cookie as a Default Persistence?

When you use Source Address Affinity as a fallback persistence method, is not uncommon that appears that the BIG-IP system incorrectly distributes more requests to a particular server. The BIG-IP system uses the fallback persistence method when it cannot use the specified primary persistence profile. In this case, cookie persistence is configured with source address affinity as a fallback, but if a client does not send a persistence cookie, the fallback persistence method is used instead.

Remember that when a cookie persistence profile is configured for a virtual server, the BIG-IP system does not store the session data locally in the persistence table; the BIG-IP system stores the session data in the cookie.