Wow. An ISP going down the route of enshittification by taking away networking basics is not something that i would have expected years ago, but nowadays i am only sad about it.
My ISP wants me to swap out my modem, but as long as it works i won't do so - i fear they might take away my (officially dynamic, but only changing once in a blue moon when they make changes in their network topology) IPv4 address and stick me back behind the awful CGNAT they have as they did once without asking years ago.