Uncheck " EnableTCP Resequencing" in the Firewall policy- Traffic and stealth settings.
Log into the Symantec Endpoint Protection Manager.
Click on Policies, on the left.
Select Firewall Policy.
Double click on the Firewall policy assigned to groups and locations.
On the left hand side, Click on Traffic and stealth Settings.
Under Stealth Settings, Uncheck "Enable TCP resequencing" .
Click OK to close the window.