I’ve been having issues with Internet browsing through Squid (way before posting this issue, so I think is not related), from connection timeout in clients browsers (Firefox mostly), to slow pages rendering and proxy error form client browser.
I believe this issue might be related to DNS resolution, DNS response taking to long or Squid trying to use IPv6 and then changing to IPv4.
config set dns configuration NameServers 188.8.131.52
On my AD DNS increased timeout response to 10 seconds
I did this yesterday on so far no one has complained again, should thing keeps like this, this week I will put this as solved.
BTW, I have a question, while using proxy, who actually ask for URL DNS resolution? Is it the client PC or the proxy service?