HomeKit issues w/Wemo switches

Hi there,
I’m having trouble with HomeKit and my Wemo switches… the switches seem to be failing one by one in that the switch physically still works, but I can’t get them re-added to HomeKit after moving / disconnecting them, or they’ll just stop being accessible through Home app. It’s now happened to four of the eight that I have. I’ve tried factory resetting the switches, updating their firmware, etc., but nothing seems to work… Anyone have a similar experience? Is it worth starting over w/HomeKit?

I have 2 of the older Wemo switches that use the hub, 2 of the newer ones with HomeKit compatibility built in, and a few from other brands, including two from Vocolink. The two older Wemo ones are completely unreliable with HomeKit. I have to regularly unplug and replug either the plug or the hub to get them working. I’m on the verge of just getting rid of them, and buying a couple more Vocolink plugs to replace them.

I had a couple of the older switches that I used with the Wemo bridge. I had the same problems. Had to reboot about one a week. I have three of the v2 switches and three of the plugs and have little or no problem with them.

What is your Wi-Fi network? Are you using a classic Wi-Fi router or a newer mesh system?

The Wi-Fi router/access point manufacturer and firmware can make a difference in reliability.

A common symptom is a Wi-Fi HomeKit device will work for a few days or weeks, then need a physical reset before it will work again.

In this scenario, it is still configured in HomeKit, but unresponsive until physically rebooted.

The problem can happen with many brands, not Just Wemo. It seems to be related to HomeKit only and not general Wi-Fi switches that are not HomeKit.

Further ad hoc research points the finger at the mDNS protocol which is used heavily by Apple, and not used by other smarthome devices.

Unfortunately, many Wi-Fi systems have poor or flaky firmware handling of mDNS. Updated Wi-Fi firmware (not the switches, but your Wi-Fi gear) will usually fix the issue, but I’ve seen working systems brought back down to unreliability by new firmware so it requires careful testing. Never update firmware in routers or Wi-Fi automatically if you have the choice.

If you suspect this is your problem, get one of the free mDNS “Discovery” apps for iOS or macOS.

The mDNS keys you want to look at are “_hap._tcp”. You should see your switch listed there when it is working. As soon as it fails, you’ll see it is no longer listed.

Since mDNS is the failure, if you write down the IP address when it is working, you can often still “ping” the device even when HomeKit fails. This empirically further confirms that the device is still “on the network” but unable to communicate with HomeKit because the mDNS discovery/response is no longer working.

(Sorry is the above is too technical; if this makes sense to you it can help in diagnosing and troubleshooting.)

I suppose it could be an mDNS issue although I haven’t seen any symptoms on any other devices (e.g. my NAS). (To answer your initial question I am using the Orbi Mesh). I assumed for a while that the Wemo bridge got confused when DHCP leases expired on either the switches or on itself…but that was just conjecture. Doesn’t matter now though — i replace my 2 V1 switches with V2 switches and decommissioned the bridge and the world is good :slight_smile:

NAS doesn’t use mDNS the same way so wouldn’t expect any problems with a NAS. Easy to check with a “Discovery” app: run it when things are normal to take a baseline view, then run it again when the plug stops working.

If it has disappeared from the hap section (“HomeKit Accessory Protocol”) it points the finger at mDNS.