I haven't had DSL in a while, but when I did, the ISP just provided a modem with a phone line connector and a single ethernet connector. There's no requirement for DSL to bundle the modem and router.
Sure, lots of DSL ISPs used to do that in the old days before WiFi was a common consumer demand, and some still might.
Now, the ISPs that are using DSL (e.g., AT&T U-Verse which uses VDSL2 where it isn't FTTP) seem (from what I've experienced and seen with other people that have DSL-based service) to deploy all-in-one modem/routers (and, when they have services like TV and Phone as well as basic internet, to run them through the supplied all-in-one box, as well.)
> There's no requirement for DSL to bundle the modem and router.
Sure, its not a theoretical requirement, just practically what ISPs seem to do now.
Gotcha, I thought it was being presented as some sort of technical constraint.
An interesting variant on all of this is FiOS, which is often brought into the house on coax which plugs into their router. It's possible to buy something that will bridge the coax to ethernet, but they're pretty hard to find.
I think this might be going away as they increase speeds. I originally had the coax, but then they replaced it with ethernet coming in to the house. I kept their router anyway because it actually seems to be pretty good.
