If you buy a house before wiring for network was common, you can check the phone outlets. A lot of homes use Cat 5 for the phone cable so those outlets can be repurposed for networking.
Another (albeit, terrible) solution is HomePlug[0]. I once had broadband installed in an apartment and was provided with a couple cheap "ethernet over power" wallworts. I think the tech has improved, but they seemed to get a massive amount of interference (I think they capped out at like 65mbps?). I think I lost connections whenever the microwave was turned on.
My houses wiring is pretty new and although my homeplug units are advertised to run at up to 500mbps, I get about 300mbps out of them which isn't terrible.
I have the cat5e throughout the house but in a ring topology as it was wired for phones only. RIght now I just have two points connected end to end. Next step is to think of a clever way to use the 2 unused pairs to support another 100BaseT and create a fake hub and spoke topology. This G.hn standard might be a good way to get even more performance out of this setup.
This was one of my highest priorities after buying my current house and it was well worth the effort.
The cable line in my livingroom connects to a modem. The modem feeds into a wifi router so that I get a good signal throughout most of the house. One of the ports in the router's on-board switch feeds into a wall outlet, which connects to a master switch in the basement. I could never go back to pure wifi.
What I find strange is that, like the OP said, the original network was setup for phone outlets... but the house was only a couple years old. Are RJ11 phone networks really still a bigger selling point than RJ45 switched networks? With the high adoption of cellphones and the increasing demand for internet-connected devices, it seems like RJ45 should be standard.
I recently bought a house built in the 1960s. It's surprisingly easy to add Cat6 to an older home as the interior walls aren't insulated. I've been adding drops as needed and it takes me about 30 minutes start to finish to run a new drop.
I'm out the cost of materials (maybe $200?) and the price of having an electrician add an outlet to my "MDF"/hall closet ($175).
Dont forget about powerline-to-ethernet adapters, esp if you only have a small number of devices or dont need full gigabit bandwidth. experience varies, but if the two endpoints are on the same breaker, you can get > 100mbps, and if it has to cross breakers, you can (potentially) still get over 1mbs, which is enough for streaming and basic surfing. Much easier than running wire or messing with drywall if you're not handiman-inclined.
If that doesn't work, and you either don't look up often or you don't mind a little ugliness, I've found running cable along the tops of walls near the ceiling works pretty well, and is easy to do. Here's part of my home network cable run and also part of the speaker cable run for the right rear surround sound channel [1].
Where a cable needs to make a turn to follow a corner, I screw in a cup hook. For support along a straight section of wall I nail a wire nail partly in and hang the cable on the protruding part.
If you want to do the work, adding in crown molding after running some cat6 can make the room look much nicer if the style fits. You can then drill a hole in the drywall at the top of the wall, drop the cable down between the studs and install an actual outlet. Crown molding usually has a decent amount of space to run a few cables.
As others have said, crown molding can help that. Also, there are flat cables that can make running cable between baseboard and carpet (and even under carpet) virtually invisible.
Staples leave small holes when removed which are easy to patch. You can also use many of them to get nice straight and tight runs. You can put a bit of white (or whatever color your walls are) paint on them to help blend in.
It's not ideal aesthetically, but nice straight lines and right angles go a long way to making it look better. The next step up would be to run some channel to hide the wires, but I don't find that necessary.
Careful with the staple gun. Some of them are more powerful than you might think, and are potentially capable of pushing the staple through the insulation and providing a nice conductor to connect the wires. It has happened to me.
That’ll depend on how or if they daisy chained the phone jacks. You should be able to get at least one Ethernet connection (two ends) but beyond that you might have to get creative.
If you put your modem at the same jack where the first tee in the line is, you should be able to get at least two connections, but for more than that you may need a switch at each tee.
