We can't stream videos because of constant buffering. My husbands iphone keeps showing no internet connection.
When you open the modem's page (http://192.168.0.1/#!/home/status), what's the state code you get?
0.0.0 -- Fully operational
What have you done in terms of troubleshooting? Things such as rebooting the modem and all the devices connected to it, switching channels, downgrading the video quality, suspending the Video Data Saver, etc.
Does this buffering happen at all times of the day or is it more common in the evening?
I hope one of the mods on this site will get involved -- they may have more suggestions for troubleshooting.