My primary issue consisted of unpredictable loss of 'reachability' to different bulbs. This can be seen the Philips Hue app as lights with a (!) symbol next to them.
After much googling I found some things to try to resolve this issue.
Easy - Turn light off and back on
1) Turn the light off and back on. Wait a minute. Sometimes the light would rejoin communications.
2) Repeat the above until it worked... when step (1) didn't.
*Save this one if nothing else works - Bulb Reset - Discovery
Time consuming...potential headache... may not even work...
1) Try a different Zigbee channel. Turn all lights on (make sure the power is on). Use the Hue app to change the Zigbee channel. Go around and test the lights. Under Settings>Lights>tap each one with a (!) make next to it and see if the light flashes on and off. If so, click ok, and it should be back in contact. If not, then having to trigger a reset on the bulb (differs by bulb but usually something like turn on, wait a few seconds, turn off, wait at least 3 seconds, repeat 5 times). The light will give a sign that it reset (GE Link bulbs fade and then go bright, Hue flash (if I remember)). Then running the auto detection routine in the app (light will flash when detected), name, and should be back on.
Alternate version - perform a reset on the Hue bridge (reset button is on bottom)
Next reset the bulbs using whatever method is used for your type of buld
Use the app to discover the bulb.
I don't recommend either of the above two approaches unless as a last resort. Especially if you have a large number of bulbs. This will take a long time to get fully back up and running, if it succeeds.
When the problem manifests somewhat randomly, and at times works, or at least only affects a small number of bulbs, troubleshooting is a great first step.
- Did the problem start after a software/firmware update to the Hue bridge?
- Did the problem begin after some kind of change?
- Have diagnostics been run on the home network to ensure it is working problem?
- Anything documented online that matches your situation and has a good solution?
- If using a mix of brands of bulbs, are the problems limited to a certain brand?
To make this short... I did all of the above, I spent much time trying to find a pattern, a change to my environment, or anything potentially defective.
Essentially, I believe I may have found the problem. Although the Hue bridge is using Zigbee to communicate with the lamps, it also shares a frequency spectrum near enough to WiFi signals that interference is a potential issue. Well, if you really want to boost the RF interference, put the WiFi network device, and the Hue bridge near each other. Proximity increase the potential, or real, RF interference. By creating interference, the Zigbee network suffers significantly. So after thorough troubleshooting, my issue was having a WiFi AP too close to the Hue bridge.
Oddly, this was not something I really came across while researching the problem I was experiencing. It was not until I read a research paper on the potential interference be 2.4Ghz Wifi and Zigbee that I realized my AP and bridge may be too close (approximately 3 feet).
But, I should point out this was a recent change to my environment, yet I have had these issues on and off for a good while. Further, the AP was still somewhat close, at about 6 feet. So I would say most of the time the AP has been fairly close. Today I moved the WiFi AP to another room, about 24 feet way from the Hue bridge. I then when to each like that had a (!) next to it in Hue app>Settings>Lights and turned the light off and back on. After about a minute the (!) went away and I regained control of the device. This went relatively smooth and quick. I would say this was the most positive sign I have had regarding stability and easy of communication among the devices connected to the Hue bridge.
Although I made this change just a few hours ago, the way things went so easily and quickly, it makes me think this may have been the predominant issue.
I should add that a while back I did add more bulbs to my environment to ensure that the mesh network should have adequate proximity between bulbs and a reasonable changes to form good signal strength.
To sum, I wanted to get something posted right away in case it might help others. I am very tired and realize this may be poorly written and a bit confusing.
I'll come back and review when I am rested. So, when troubleshooting an unreliable Zigbee mesh network, include RF interference as a culprit between WiFi and the Hue bridge.