Internet Connection Isn't Working On PC?

As I said my pc connection is just freaking f***** up. It works on my other Pc's but not on my primary one. It works like this, it works for an hour, day maybe even a week but sometimes it just wont work, i plug the cable in it works for like 1 minute or two, sometimes an hour or maybe a little longer, but at the end it just dissconects from internet i replug my cable and again working or not for a couple of minutes, something has to be on my pc do anybody knows what, though my PC is optimized and very well secured and from time to time cleaned.