Normally, the printers are compatible with the 2.4GHz Wi-Fi band, so we recommend trying to connect your printer to the 2.4GHz network.
If you're still unable to connect, we suggest adjusting the security settings for the 2.4GHz network. You can do this either through the SURFboard Central app (if it’s already set up) or through the web-based interface (GUI).
For your reference, please follow the setup guide provided in the link, which has the steps to change the security type either through the SURFboard Central app or via the web-based interface (GUI).
http://arris.force.com/consumers/articles/General_FAQs/G34-G36-Unable-to-Connect-to-the-Wi-Fi-Network