Roku Ultra won't connect via Wired connection

I had the very same problem with a new Roku Ultra (4670X) and tried resetting the modem and the ONT and the patch cord without success. I plugged the Ethernet cord that my Roku Ultra wouldn't recognize into my laptop and the laptop worked just  great. I am using a  GreenWave C4000XG router on a CenturyLInk fiber optic 940 Mbs connection,

Here's what worked for me.

1. I logged onto the router (http://192.168.0.1) ignoring warnings about it's not being a safe site
2. I went to “Advanced setup\Security\Application Forwarding”..
3. In the “Select Device” drop-down box, I selected “Roku Ultra Family Room”.
4. In the “Application Category” drop-down box,  I selected “Applications”
5. In the  “Applications” drop-down box,  I selected “Windows Media Streaming”,
6. Don't forget to click “Apply”
7. The router created two entries in the Application Forwarding List with TCP-UDP ports1755 and 7007 for the Roku Ultra Family Room device.
8. I tried “Settings\Network\Set up connection\Wired,” and the connection occurred within seconds.
9. Here's the weird thing: I installed a Roku 3 (4230XT) to a different TV, anticipating that it would not connect until I entered another Application Forwarding entry into the router for this Roku 3. Oddly, it connected right away without any entry into the Application Forwarding List.
10. I removed the entries from the Application Forwarding List.

It's only been 3 days since this "fix" but I did reset the connection with 

“Settings\System\Advanced system settings\Network connection reset\reset connection” and it restarts all nicely connected to the wired connection. '

Can anybody explain this behavior?

Jay