C6300 wifi 2.4ghz and 5ghz The speed of the Internet will drop randomly.

I used time warm cable service,Recently,I upgraded my network plan is 100MB, connecting 2.4ghz or 5ghz wifi , for example, I went to ping wwwgoogle.com-t appeared sometimes “Request Timed Out”, about five minutes there. I thought it was set up the problem, restore factory settings, but the problem still exists, before my network service package is 30MB, without this problem, my firmware is the latest!