Diagnose interference causing garage door opener remotes not to function
Excellent article!
I just had my GDO remote drop from 30+ feet range to where I had to at the garage door - and it took several tries to  cause the door to open.
I had just installed a wireless indoor security camera and that was the culprit - unplugging it removed the issue.  I tried various increases of GDO antenna length but no improvement.  I was in the process of using a window screen on the opposite side of the wall when I found an article about an RFI kit - rather than buy the kit which was a tad pricey, I bought several 5mm ferrite cores that snap onto wires. 5mm based on the diameter of the wires they'd be used - they come in sizes 3mm to 9mm and possibly larger.  I tried the camera power cord and there was no improvement - I then put a core on the manual switch wires where they connected to the GDO - that bought me another 8 feet of remote range.  I then also added ferrite cores on the same wires near the manual switch and I'm out to 25 feet.  The camera must be throwing off harmonics of the 2.4 GHz signal and the manual switch wires were acting as antennas.  I'm still going to place the metal screen on the garage wall opposite the camera location in the house to try to block the RFI more yet.  I hope this helps anyone with a similar situation as these cameras are more and more popular for nurseries, pet surveillance, and home security.