A:Answer From Spectrum website: ( https://www.spectrum.net/support/internet/compliant-modems-charter-network/ )
Minimally Qualified Modems
You may also choose to buy a modem that has passed minimal testing to confirm that it won't cause harm to our network. Though permitted for use on our network, we recommend against using Minimally Qualified Modems because they haven't been tested to confirm their ability to deliver your purchased internet service speed.
Note: If you attempt to install your own device from our authorized modems list that doesn't meet the speed tier you ordered or if we can't determine the device qualification, you'll get a message that notifies you of this, and you'll be asked to acknowledge this before you proceed.
Below are the Minimally Qualified Modems that have passed the limited no-harms certification testing.
Arris SBG8300