Wireless router troubleshooting/recommendation

I just found out that my WiFi router kill my Gigabit Intenet connection. If I bypass the router, I get 949 Mbps on speed test. BTW, thanks to whomever made the troubleshooting video. I tried to bypass the router before for testing but did not know I needed to reboot the modem when switching devices so that did not work. Spend all morning chatting with Xfinity tech support but they did not know or say anything about that. 

With the router inline (wired connection, CAT 7 cables), I get only 350 Mpbs. My router is Netgear R7900. Its Ethenet ports are Gigabit so theoretically, I should be getting close to what I have on direct connection to modem. I expect some overhead but not losing close to third of the bandwidth. 

Was anybody successfull getting Gigabit speeds with this or similar router. Are any configuration adjustments on the router that would need to be made? I updated router firmware yesterday to the latest version. Finally, any recommendations on what WiFi router would get me Gigabit speeds on hardwired connections? I would rather get my router working but I am not opposed to replacing it.

Thank you