Not getting 1GB connection from x6 R8000 nighthawk router

[kamikazeedragon]

I recently got 1gbps fiber coming into my house.  For some reason, I cannot get above 300mbps out of the router.  I don't have anything special setup.  I've run tests from a computer connected to the fiber line and that all comes out ok.  However, I can't seem to get the full speed from the router. I tried setting my speeds manually, but as soon as it applies it goes back to "let speedtest detect my speed."  The advanced statistics show 1000MB/Full for the WAN.  The 5g WLAN report 1300M/Full.  

I do not have QOS running.  I turned off network monitoring.  I do have Bitdefender running, however shutting it off did nothing to help.  Do I reset the factory settings on this thing, or go replace it with a newer one?

Thanks in advance for your help/suggestions.

[plemans]

Qos, traffic monitoring, parental controls aren't recommended at speeds >250mbps. 

And I've heard of their settings being retained even though disabled and rebooted. 

I'd try a factory reset and then during install, only setup the things necessary to get it working. Then speedtest.