>>30792
That uses more energy. Only makes sense if you use some kind of general-purpose computer (old PC, Raspberry Pi, etc) that doesn't speak DSL as your secondary router. If your secondary router has a DSL port, just remove the ISP router. DSL is standardized, it should work. If your secondary router is not recent enough to support whatever DSL standard your ISP has, it's probably a bit crap anyway (no 5 GHz WLAN, no Gigabit(+) ethernet).