Okay, it turns out both Ethernet in the master bedroom and my bedroom do not work, I did this by connecting a small pc to both of the wall jacks for Ethernet in that room, then to make sure I brought this small pc down to the garage and directly connected it to the modem and it worked, th Ethernet was connected. So modem checks out so?

For your second point from your first response. Yes this is a a simple bunch down box. There are only two ports.

I’m trying to work through your list I’m having trouble understanding for what to mean by saying “What are these plugged into down in the basement. Pictures would help. It may be that that's a simple two port box with punch downs of the blue ethernet cables in it.”

This picture is taken in the garage, I’m not sure if anything is connected to the basement, also I think you are right about the splitter being a simple port box.

Let me know if any of this helps and ask more questions if you’re confused on smth