Known Issues with R6000-series routers? 3 failed devices

Hello,

Has there been known issues with with the R6700/R6900 models?  Between my family members and I, we've been through 5 of these devices which seem to only last 1-1.5 years before their dead and won't boot.  I'm "tech support" for the family and have personally been through 3 of the 5 myself.  My family members live a few hours away, so I have to make trips to replace routers every year or so. 

Most recently, my parents' R6700 factory reset itself, or at the very least, reset the WiFi config back to the default "Netgear45" as the SSID and they had to use the default password from the sticker on the bottom of the unit.  2  weeks later, their network would crash each time they tried to connect their Amazon Fire tablets to the network.  I ended up replacing it with a different brand and they are up and running at least.

I'm having a hard time recommending Netgear at this point.  Were the 6000-series models just that unreliable for long-term use?  Are the newer models better in that regard?