(straight from email)
• We’re adding a term to make sure our customers use equipment that complies with relevant standards.
• We are adding a right to slow your service if we reasonably believe you’ve breached our Acceptable Use Policy.
• We’re adding more definitions to what we consider ‘unfair, unreasonable or inappropriate use’.
• If a customer treats our people in an abusive or threatening way, we may end the interaction and – in extreme cases – we may stop offering our service to them altogether.
Your router isn’t a modem, they don’t care what router you use.
Not sure what kind of ISP these guys are, but I’m assuming coax based, in which case they probably are adding terms saying you need to use more modern DOCSIS modems. This is most likely because they are going to start to phase out support for older DOCSIS standards.