I get no interference from my microwave oven on 2.4GHz.
I did try putting some water in the microwave and running it while my laptop was pinging the default gateway via a 2.4GHz wifi connection.
No packet loss at all.
Then I started pulling on the door at the top edge away from the hinge.
I was able to make it start dropping packets by pulling on the door with just a little force. Not enough to make it pop open, but just enough to distort it slightly so it compromises the shielding and allows 2.4GHz RF leakage from the microwave.
The harder I pulled, the more packet loss I saw.
As soon as I let go, the packet loss stopped.
Conclusion: A properly functioning microwave oven causes no interference to 2.4GHz wifi.
However, even the slightest warpage of a microwave oven door is enough to compromise the shield.
Therefore, if your microwave oven is causing 2.4GHz wifi interference, there is a good chance that something is wrong with it. Replace or repair as needed to remedy the problem.
Is your microwave 1/2 way between your laptop and router and signal to the router isn’t great to start with? Test like that. I will guarantee interference. Dont be pulling on the door... :-)
A Federal standard limits the amount of microwaves that can leak from an oven throughout its lifetime to 5 milliwatts (mW) of microwave radiation per square centimeter at approximately 2 inches from the oven surface.
Given power drops off at something like a power of 10 at distance, and that routers are limited to 80mw in the 2.4ghz range, and that for both the router and microwave 2 vs 20 inches would be approximately 1/100th of the value measured at 2 inches and that microwaves have a very large radiating surface... QED.