This question was inspired by my hatred of Temporal Anti-Aliasing which, in many games nowadays, is poorly used as a performance bandaid. On lower resolutions it will smudge and blur the image and certain bad cases of TAA will cause visible ghosting.
Yet in spite of all this, certain games won’t let you turn it off or have hair/fur/foliage look like dogshit without it so sometimes I still use it.
If you can’t ditch their modem without problems, then usually you can still set it to just transparently forward traffic to your own router. Setup is usually not hard if you have an extra network cable and a computer with a network port (and many can be set up with a smartphone these days)