slow performance tns helper (port 1521) after upgrading

Hello, we have a strange issue with a customer.

They upgraded

Since the recent Fortigate upgrade from 4.3.12 to 5.0.12  , customers notice a huge degredation of performance in the software, connecting from Solaris 10 to the Oracle server on port 1521. When doing a packet capture, we notice a lot of retransmissions and duplicates. Remarkable is the fact that, when the Fortigate is bypassed there are NO problems.

I discovered also that by disabling the tns session helper for tcp 1521, things run smoothly. I logged a ticket with Fortinet, but they cannot give a satisfying explanation for this. I was wondering if someone has had a similar issue and what makes that there are no errors anymore when the session helper is disabled.

Thanks and regards,

Ralph Willemsen

Arnhem, Netherlands