My house used to be connected to Comcast before we switched over to a local fiber ISP. This switch has happened years ago and the house was outfitted with coax back in the Comcast days. Of course now, there is no use for Coax. The local antenna stations are not great and we don't have cable coming in either. So I figured that I would replace our existing coax with ethernet.
We have three coax ports. One in the basement that goes outside along the wall. And two in the house that share the same wall across two floors. The basement port was very easy to replace as I just had to poke the ethernet out the wall and re-enter into the boiler room—where the networking is located.
I'm still planning out how to replace the two remaining ports. My original plan was to attach the existing coax cable to the ethernet cable and pull it through the wall up into the attic without having to cut any access holes. This would work great in theory, but I have found that there is only one coax cable coming into the attic. This means that somewhere in the wall is a coax splitter.
I'm not entirely certain that this is how the cable was installed, but it seems that way. There are two possible solutions that I can think of to make this work: Make the existing access point hole bigger in the attic so that I can pull the splitter through and not have to cut the walls. I could remove the box on the second floor and remove the splitter from that access point and replace the box in the future.
If I were to cut in the attic, it is possible that I will reduce structural integrity. If I were to remove the outlet box, I may have to make repairs to the wall. The box may not be attached to any studs, free floating on the drywall with mounting ears. This might make it easier for me to remove the box without damaging the wall.
When I get the chance, I'll try to remove that box and see if I'm right about the splitter.
Update - Retrofitting telephone wire
alextheuxguy responded and said that he was lucky that the phone jacks were wired with Cat5e. That's pretty cool! And now that I think of it, when I was last in the attic I saw some mysterious 8-wire unsheathed cable up there that looked suspiciously like ethernet. I know there is a telephone jack in the dining room, so maybe I would also be able to retrofit the telephone jack with ethernet.
I'll have some more investigating to do.
Thanks for the tip Alex!