R6700v3 New Firmware Slow Speeds

Frustrated with this product ! First tried to install the router with the Netgear NightHawk app, but the QR Code scan option would not work, (kept saying that the QR code was invalid... so I had to fallback to the manual setup steps.

But after getting the setup ok, I kept testing the IP Speeds of the WiFi connectins (via the 2G line) and was underwhelmed....only 50mbps or so download speeds to my Roku device. I then checked the ethernet port speed to my PC (which should reach up to 400mbps) and found that I was only getting around 150mbps at best.... 

I thought perhaps that it might be a simple tweak in the router settings, so I started researching here on the web looking for tips on how to increase router speed settings....tried several things, all which didn't seem to help...several updates of the firmware to latest versions....many reboots of the router....reconnection of lines....tried different ports....etc. etc....

I finally found these posts about reloading of the firmware to the previous version, and thought "Why should I need to do that for a brand new product?". I'm not an expert on all this stuff by any means, and don't feel very comfortable with reloading the base software. 

I eventually was successful at restoring the firmware back to v1.0.3.66_10.0.50. 

The speed to my PC is now +-450mbps (which actually is greater than the advertised speed of my ISP service)!

So I'm only out about 5-6 hours of my time trying to debug/setup this router. I plan to return it for a full refund. I will be looking for a brand other than Netgear for my next purchase.