Symptoms

  • Users experience gradual and increasing loss of email traffic.
  • User is unable to download the Outlook Profile Helper properly.
  • Eventually, connection to the Exchange server is unavailable.
  • Connectivity to the FTP site may be affected.

Internet access to other resources is not affected. A power cycle of the modem can resolve the issue for a short period of time.

Cause

Some modems that Comcast utilizes for Business Class customers have both Firewall Protection and Gateway Smart Packet Detection enabled. Secure traffic, such as HTTPS used by Exchange, will stop working as soon as the Smart Packet Detection identifies this type of traffic. Smart Packet Detection can take from minutes to hours to start blocking the traffic, until it eventually blocks it entirely.

Additionally, the modem firewall combined with antivirus protection on the workstations can cause a double firewall condition that may also affect performance.

Resolution

Turn off both Firewall Protection and Gateway Smart Packet Detection on the Comcast modem.

Please contact Comcast Support if you are experiencing the described symptoms.