it would be great to purchase directly from Netgear power supplies for routers like they are doing at Dell,
The strange thing a wndr3400 power which is a switch mode power supply least for years in must cases I believe the true problem is not the power supply itself all switch mode power supply convert ac to dc and drive a transformer to product the normal 12 volts that most netgear routers use.
The problem is the people who make the power supply and the quality of the parts used a part rated for 85 degrees will not last of long as rated for 105 degrees. Heat can break down anything if heat enough and long enough.
I have found that the longest lasting and easiest t find are laptop style power supplies they have bigger heat sinks and better design on ebay.