This is all very hypothetical unless op comes back with more information. Could be his microwave causing this for all we know.
It is correct. I was careful with my choice of words. Please take them at face value and don't read into them something not there or what you want. For example, I never suggested anything close to "military grade Jamming" which - for the record, I am personally very familiar with having spent 24 years as a military radio communications equipment technician (as noted via the link in my sig) supporting a vast array of real-world and exercise events involving jamming and jamming countermeasures, here and abroad.
And please note what I wrote that you quoted. I said it is "highly unlikely" a motherboard in one computer would affect the entire network. That is absolutely true. But "highly unlikely" is not the same as "absolutely impossible" and the exact reason for my next sentence in that post.
True. But while 802.11n is not exactly new, it was and still is great at isolating channels and connections compared to previous revisions. I would suspect the OP has at least 11n. But again, more information is needed.
But since we are getting into the whole background knowledge here, I will say this much: I have mentioned before on this forum that I have an engineering degree in networks and security. I have experience with network architectures from coax to 5G cellular and wifi 6E. I have also done my fair share of penetration testing and prevention as per the security part.
I can guarantee you that a regular wifi network can be kept busy by most wireless devices. Wifi does not have the signal strength, redundancy, or robustness of some of that military equipment you've worked on. I am sure you know what happens to a cb radio channel if some fool keeps the PTT pressed. Wifi is about that susceptible to interruptions. Wifi is seriously limited in signal strength, compared to most other wireless communication. I don't know how many orders of magnitude stronger military equipment is, but I am willing to bet it is several.
Modern wifi standards are better as said above, but put a noisy (malfunctioning) device "near" the router and your network will still appear dead as a dodo to other devices. Beam-forming can do wonders for devices in other directions, but it is not magic. Same goes for features introduced with newer standards.
Anyway, this is really not helping op. Unless he comes back with more information this thread is dead.