Computers experience network performance problems when the Network Threat Protection (NTP) firewall component of the Symantec Endpoint Protection (SEP) 12.1 Release Update 2 Maintenance Patch 1 (RU2 MP1) client is installed and enabled. Symptoms include:

• Copying files from a network location over Windows File Sharing takes significantly more time.
• Programs that are started from a network share take significantly longer to load.
• Ping responses take longer to return.

This problem is caused by a performance issue introduced with the SEP 12.1 RU2 MP1 NTP firewall driver, teefer2.sys.

Symantec is aware of this problem and will update this document when a solution becomes available.

To work around this problem, use one of the following:

• Disable the Network Threat Protection firewall on affected computers.
• Withdraw the Firewall policy in the Symantec Endpoint Protection Manager (SEPM) for groups containing affected computers.
• Migrate affected computers to Windows Vista or higher
• Revert affected computers to the a previous version of the SEP client