Could you please help us with the model number of your product?

Please try using different Ethernet cables, swap the ends of the cables, and make sure the LED lights on the Ethernet port of the gateway are flashing.

Thank you - SBG7600AC2

I have used three different ethernet cables (including the two that were working fine before the internet outage).

The light on the computer flashes but that at the modem/router is lit but not flashing

The modem and computer have been rebooted several times

Thank you for the update!

Please try switching ethernet ports on the SBG7600AC2. 

I would suggest you try disabling the Ethernet port and then enabling it again by logging into the interface of the SBG7600AC2.

Since the wireless connection works, connect to the network, open a browser, and enter http://192.168.0.1 in the address bar.

Please refer to this link, where you can find the steps to log in to the interface.

http://arris.force.com/consumers/articles/General_FAQs/SBG7600AC2-Web-Manager-Access

After logging into the dashboard of the interface, select 'LAN Setup' at the top, then choose 'PORTS' under the subcategory.

Next, select the port, uncheck the 'Enable' box, apply the settings, and then follow the same steps to enable it again.

Please repeat these steps for all other ports.

I had high hopes for the “disabling” suggestion but, having dome all four ports and tried plugging the ethernet into each of them, the problem remains the same

The light is on (stable) at each end of the cable but the computer still cannot identify the network

Since the problem persists even after the suggested troubleshooting steps and for further assistance, we kindly recommend visiting us at www.arris.com/consumersupport. 

Noted - thank you