Why do I get Request Timed Out response?

[wisdomseeker247]

Why do I get Intermittent Request timed out response when I am PINGing website such like http://www.google.com?
This is my current network setup, I have a Modem which is connected (of course) to the Internet, and a Router connected to it. If I connect my PC directly to the Router or Modem I don't get RTO response, but if I connect the other departments which are under the Sub Switches, and those Switches are under the Router I can get RTO, Why is that? Thanks in advanced for the help.

[pri✍]

I think you should address this question in technology, networking, or something like that, definitely not in Facebook category.