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If everything works well you should see first Cable Modems requesting DHCP (DISCOVER, OFFER, REQUEST, ACK) followed by Named and tftp config file download
5. Check
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DNS
Check if you can resolve cable modem hostname via ping, like
...
Then check the /etc/resolv.conf file. There should be NO hostname statement with an external DNS IP inside of it.
6. Login to GenieACS
https://<your-url>:8080/genieacs/
Run wizard and change default credentials