The number one cause of buffering is poor network connectivity. This may not be a problem with your network but may be caused by your Internet Service Provider (ISP) getting overloaded. This is especially likely during peak usage hour.
If you experience excessive buffering after 15 seconds to 1 minute, no matter what you try, you may be experiencing a firewall problem. The problem has to do with the way some firewalls handle streaming traffic. To fix the problem, you must update your firewall’s firmware. For instructions on how to update your firewall’s firmware, contact your firewall vendor. They will be able to provide you with firmware updates and easy to follow instructions on how to install them.