Why does Squid3 stop working intermittently on Ubuntu 13.10?

Question

Squid

The bottom line is that I'm not strong in Linux and did everything according to the manual.
Minimal changes have been made to Squid.conf, here. That is, there was no work with the cache and access rules at all. The proxy is not transparent.
At some moments, Squid does not allow network computers to access the Internet: an error is displayed in the browser on the network computer, saying that the proxy does not want to work. Five minutes later, everything is restored. What could be the problem?
I tried to google - it does not google, sorry. I'm not asking you to give a ready-made solution (but it would be nice), you can simply direct it in the right direction.
Thanks in advance for any help.

Answer 1

The issue was resolved, the problem was on the surface: there was a router on the network that had the same IP address as the proxy server.