A good way to pass an Ethernet cable is via the base board (I mean behind it). So you have the wall box installed. and the Ethernet goes down to the floor, where the behind where the base board is. This way once you put back the base board, it's all hidden, and it will look like you have Ethernet installed in the walls since day 1, and it also avoids making holes everything in your walls to pass the Ethernet cable around, especially if your wall studs are in wood and not in metal, where you don't have predefined holes. Which at this stage it will be easier to just remove the wall entirely, install the Ethernet cable, and put in new drywall, and paint. So base board trick is a nice solution. Please note, do this for ONLY Ethernet cables. NEVER with power. If water gets under the base board, it will be quite a shocking event for everyone.
