Well, we are going to answer this question, although, as a preview, I will tell you that no, a PC does not affect the router nor will it generate interference in it, although its placement will, so it is important to know where we will place it.
Does a PC attached to a router interfere?
As we have already said, no, it does not interfere, at least at the level of waves, radiation and causes that you may be thinking about. The computer acts like any other object, however, the place where we place the router can affect it, and, therefore, we think that the PC is the one that is generating signal loss to the router.
For example, there are many cases in which we have a piece of furniture, where the computer tower is placed, and for convenience or simple aesthetics, we place the router on top of it. This can cause problems, first due to cooling, since the computer emits a lot of heat, but the router also, therefore, they are not helping each other. Although the most important thing is not that, but its visibility, which will be reduced by the sides of the furniture, as well as the part in contact with the PC.
So… Where do I put the router?
Well, now that you know that a computer does not interfere with the router, but only its location. What is the best place to put it? Well, as you will understand, as with any other device, the best place is alone, away from any other device, furniture or object (at least 25 centimeters from each side). In addition, the air flow is fluid and can be cooled, and the place is not full of dust or other dirt.
In short, a cool and dry place as they say for food. And that would be it. You just have to place its antennas well and clean it from time to time. With that you will have the best connection and signal possible. So remember this and do not place your router on top of books, next to other equipment or in full light, think that it needs its space and comfort as if it were any other equipment.
And even if you are only going to connect it by cable, and you don't care about the WiFi signal, it is not advisable to place it in a very covered place, it will heat up more and collect more dirt, something that also influences its final performance, it is connected to your PC wirelessly, or not.
And you, did you know this, or did you believe in the myth that a PC interferes with router signals? Now that you know, you have no excuse not to place it in the best possible place. You will surely notice the difference. You may reach places you didn't before.