HALF SPEED ON XR700

My XR700 router is blocking internet speeds less than half of what I am paying my ISP for (350 mb down actual vs 1000 mb down paid for) with the following specs:

• Sparklight 1GB internet
• Arris SB8200 2GB modem
• Netgear XR 700 router
• Wired imac

If I plug the ethernet cable directly into the modem I get roughly 915mb download speed. As soon as I wire into the router I get less than half of that (~350 mb download speed). I had Sparklight technical support come to the house for service (twice) and they confirmed it's a router issue both times. 

Here's what I've tried with no changes in internet speed:

1. Reset to factory settings
2. New setup configuration (router noted that internet speed is ~950 mb download upon running the internet speed test built into the setup)
3. Downloaded latest firmware
4. Turned off all features (QoS, geo filter, etc) 
5. Tried to download specific firmware updates noted by the netgear community
6. Reset back to factory settings, again. 

I tried calling Netgear customer support but they want me to spend hundreds of dollars to fix a router I paid hundreds of dollars for. Any ideas netgear community? Or should I throw this hunk of garbage in the trash and get a Asus router?

Thanks