Error: "Network error (tcp_error)" when browsing the Internet; 503 error returned to the client
Last Updated January 17, 2019
When browsing the Internet you see the error:
Network Error (tcp_error)
Request could not be handled
In a packet capture, you see a 503 error returned by the proxy to the client.
There are several reasons why you may see the "Network Error (tcp_error)" message:
For a new implementation or topology change, the IP gateway may be misconfigured.
There may be a Layer 2 or Layer 3 loop on the network
Asymmetric routing or something upstream is not passing the proxy's traffic to the Internet
Consult your Symantec Sales Engineer or Reseller if this is a new implementation, or if there has been any topology change that affects traffic flow to or from ProxySG.
If the problem occurs with a specific URL or destination, it may be due to one of the following:
3-way TCP handshake fails between the Proxy and the Origin Content Server (OCS).
A reset (RST) packet coming from upstream towards the proxy on a specific tcp session.
Something upstream is not passing the proxy's traffic out to the Internet.
Layer 2 or Layer 3 loop on the network for a specific URL/destination.
When this problem occurs, obtain a packet capture; it is very important to see what is happening on the wire. To take a packet capture from the proxy, go to https://<IP.address.of.ProxySG>:8082/PCAP/statistics.
Download Wireshark to view a packet capture taken from ProxySG.
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