Dlink DGL-4500 Firmware Update Fountain Valley, California

Ever since updating the firmware on my DGL-4500 router to version 1.21NA which is posted on the company's website (see link http://www.dlink.com/products/?pid=DGL-4500&tab=3) my router no longer works the way it used to.  The router constantly disconnects and or reboots causing me to lose internet connectivity until I unplug the router and plug it back in again. This happens on a daily basis. The company states on their website (at the above link) that this update will correct several issues with the router but instead, it creates more issues.  A Google search on this issue will show that there are NUMEROUS customers with this very same issue.  I have contacted their customer support and they act like they are not aware of the issues users are having and take you through the standard troubleshooting steps (all of which I have tried) and when that doesn’t work they tell you that they need to call them to further trouble shoot the issue.  Again, please do a Google search on this issue and you will see that there is no trouble shooting this issue.  To make matters worse, the firmware update provided by Dlink makes it so that the user cannot roll back to the previously installed (and working) version of the firmware.  Why do they pretend this issue is not happening?