My motto is "Mysteries are Questions, Not Answers," which is evident when troubleshooting signal interference problems.
The WiFi Mystery/Answer
I dismissed interference as an issue because we mostly had good service even though we had an old Google Nest WiFi router sitting right next to our primary cable company WiFi router. I didn't think it was a problem, and all of our lights, switches, and smart speakers were on that router, so why change it? Over the years, we did notice several dropouts of the WiFi signal from the primary router, so much so that I scheduled a job on all my MacOS and Linux machines that logged the WiFi strength every minute. I saw the signal strength drop to single digits during one sustained dropout. I unplugged the Google router, and the signal shot immediately back to max! So now I just had to visit every one of the dozens of our Internet of Things devices and reprogram the SSID.
The unraveling of mysteries did not stop here. While reprogramming, I solved two more. One of the smart plugs was using an extension cord that only pretended to have a ground wire (which often acts to enhance the WiFi signal), so I swapped that out of a properly grounded cord, and plug was much smarter and much more reliable. The other mystery was the reading lamp smart bulb. That bulb had never worked well, and I hoped the new configuration would fix everything. It seemed to at first, but I was reprogramming all the lights in the same light socket closest to the router. When I put it back into its light socket, it didn't respond. Other lights even further away were perfect. Then it hit me: this light has a metal shade! When I tipped the lamp over and (awkwardly) pointed the cone toward the room where the router was, everything was fine. Not a good solution, but at least we know the problem.
The Bluetooth Mystery/Answer
That was Saturday. The next day, I set out to troubleshoot another bothersome issue that, again, initially wasn't a problem but had grown to be seriously annoying. I have a MacBook from work and two personal Mac Minis, all three connected to the same Bluetooth keyboard and mouse with a special button to cycle between them. This configuration has been perfect until a few weeks ago. The interface with the Mac Minis had become sticky, and the mouse was sluggish and tended to stutter. It was impossible to work with, but I never had trouble with the MacBook. Remember that this is the same physical keyboard, so it isn't sticky keys. When I moved the MacBook into the next room, everything was great. So, I rearranged the monitors and minis so that the computers were under the metal stands that supported the monitors, acting as a shield from all the interference of the MacBook. Now everything coexists nicely.
Summing Up
Creating the scheduled job to monitor the WiFi strength every minute was a massive help to troubleshooting. Logs and experiments are the best tools for troubleshooting. I have yet to find a way to get metrics on the Bluetooth, but the results from the "separate and shield" experiment strongly hint at the answer.
The WiFi and Bluetooth devices have been in the same proximity for over a year, but the problems seem to worsen over time, so there is still a little mystery. Maybe there was a software update? Maybe antennas and transceivers bleed into adjacent frequencies as they age? Keeping such equipment separate has always been a best practice anyway.
Keep looking for answers; there will always be more mysteries.
