Thanks for trying these things. Could you do this please:
In QoS, click on the advanced options in Anti-Bufferbloat. Then disable the QoS settings option (the one where it says not recommended). Click proceed when the warning message appears.
Now repeat your ping test. If the issue is solved, let us know as this means the cause is in DumaOS and we will continue to help you here.
If the issue continues, could you contact NETGEAR's official support as this means the issue will be in hardware or the NETGEAR settings section (or possibly, not even the router). Their support is 24/7 - their phone is usually the best option: http://www.netgear.c...rt/contact.aspx
Let us know how you get on!