I'd like to share some learning I acquired by trial and error, that might be helpful to others. When you log into the Cisco DPC3825 management web at 192.168.0.1 you can enter the Wireless -Radio Settings page. Whatever WiFi channel is shown, you get a statement about Interference level. Out of the box it was set to channel 6 and the interference was unacceptable. You need only try channel 1 or 11, instead. When I tried channel 11, Cisco DPC3825 said that the Interference level was acceptable. Your results may differ depending on your WiFi radio neighborhood. Since I change to a channel with acceptable RF interference, my WiFi devices have worked flawlessly. On DPC3825 you can go to Administration - Reporting - View Log. Before I found an acceptable channel, there were many vexing errors. In the month since I changed to a good channel, there have been zero errors logged.
Thanks for listening.