Where are you located? There are a lot of CL areas suffering from bandwidth exhaust. Is the problem constant, or worse at night? What is your speed using the CL test? »
speedtest.centurylink.net/What are your modem statistics? The sync rate, attenuation, and noise margin are the most helpful.
Have you contacted CL support about this? You can also send an email to: talktous@centurylink.com