I'd recommend to take a look at OPNSense and pfSense. One of the challenges of learning networking properly is that many consumer devices go into great lengths to try abstract the details away from the user. OPNSense and pfSense bring some level of openness into the situation, by letting you to SSH into the networking equipment and generally providing a web user interface with more knobs than any sane person needs. This way, you can learn by try and mistake what does what, and you'll be exposed to all kinds of abbreviations of protocols you've likely never heard of. My point is that this gives more control into how you're connected to the Internet, which serves as a great way to also start thinking about networking more holistically from the viewpoint of individual computers in your home. And you cannot really do that unless you first control the router properly.