My experience is that most DSL modems come with overly complicated software for setting up the connection, but, if you know how to get into the router, all you need is your email and password.
Also, I got my DSL modem/router for free, not that I actually use it anymore since it had a crappy switch, no Wi-fi, and only one Ethernet port.
Speaking of ethernet ports, my new router has several. What would I do with them? Maybe plug the desktop in to one of the ports for internet access? The desktop is old, and likely not wireless capable…
That’s what they are for. 
My wireless router has 4 LAN ports, of which I use 3. One goes to my Windows desktop, one goes to an old PC running a headless Linux server. The third runs to the living room, where it is attached to a small 8 port switch. From there one line goes to the Dish receiver, one to the XBox, and one to a wireless access point that doesn’t act as a router.