Actually, it is possible to enable dynamic dns support.
After enabling telnet using this
link it is possible to enable dynamic dns support. You'll need to save the page to your hard drive and edit if the NVG510's IP address if the the IP is not the default 192.168.1.254.
After telnetting to the device, you just type the following:
And then read how to set it up.
And if you need to RMA it, you would just open the complete control page again and just select to disable telnet or reset the device to factory defaults.