Internet and TV go down when cable box hdmi connection to TV is unplugged???

@XfinityVianney​ Other equipment is all connected to different outlets and on separate breakers in the house and in separate rooms.  The modem goes orange, solid then slow blink. I was dumbfounded by this one.  I am by no means an expert on cable equipment but am the elder millennial (go fix this for us) guy who has a lot of experience setting up all types of electronics, wiring for cat 5,  building and repairing PCs, etc. etc.  It will not work unless the TV is plugged in and the hdmi is connected to the cable box.... makes no sense.

@Rustyben​ I had the amplifier disconnected and the cable box disconnected and the other cable boxes and modem went down.  Tried the amplifier between all other boxes and in between modem and didn't work.  I was in a hurry to "fix" the problem so I hooked it all back up the way it was to get the internet up and havent tried to just remove only the amplifier but I assume that wouldn't work and wouldn't honestly solve the issue which is that I need to disconnect the box in the room that apparently really doesn't like being disconnected.  Fwiw, all of the other cable boxes can be disconnected without causing an issue.  It's just this one and I can check the CEC, maybe that's part of the issue.  I'm still stumped and probably going to need a comcast tech I guess.  No access to the amplifier until next week but will find the frequencies listed on it when I can. 

Thanks for letting us know and Rusty does make a good point. Is the box that you are unplugging the bigger TV box? If so, it has the tuners for the satellite boxes and why they would stop working. Normally the amplifier doesn't actually have to be on the same line as a TV box. Can you try removing the amplifier coax cable from the splitter and connect it directly to the wall? Also, if it is the big box, you should be able to just plug it in where another cable box is so it can work for the other boxes but be out of your way.