|First, check for more up-to-date firmware for your router. If there is more recent than what's on it now, update your firmware and see if that doesn't fix the issue.|
If it doesn't (or you already had the most up-to-date firmware installed) then try resetting the unit to factory defaults (info on how to do that will be in the manual).
If that doesn't fix the issue, the last thing I would do is contact your ISP and have them check to see if the modem is the problem. If they're sure the modem is fine, you likely need to replace your router.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.