Maybe he did rollback to the DHT where the on/off loop was present 
I have used @aonghusmor DHT with @erocm1231 SmartApp to synchronize but do not seem to be able to synchronize when the Aqara switches are physically triggered. The status using the DHT reflects the status but the virtual switch does not reflect the status. Are you encountering the same issue?
Are you referring to a wired or an unwired switch? On my own setup I see that the wired switch synchronizes with the virtual switch from @erocm1231ās SmartApp, but the unwired switch does not. However, that should not be a surprise as the unwired switch is deliberately set to behave as a button as far as the software is concerned, i.e. the switch is stateless; it doesnāt distinguish between on and off. The idea is that you use an app such as ABC (Advanced Button Controller) to toggle the state of (e.g.) a smart lamp, whenever the switch is pressed.
I rolled back to the 4 October 2019 version, thatās the last version that still works with single gang switches.
The on/off looping happens quite rarely, and seems to happen most easily when I toggle the virtual switch in the ST Classic app, and less often when I physically press the switch. Iāve never had the loop happen if I toggle with Alexa.
When it happens, sometimes it stops on its own after a couple of minutes of looping, sometimes I have to log in to api.smartthings and change the DTH to something else then change it back to stop the loop.
If thereās anything I can provide like logs or what let me know
Hi @aonghusmor,
Iāve scrolled through the forums and suspect from the comments that your DH is the latest DH for the QBKG03LM switch?
Iāve added the DH to my hub and have successfully added the device using the classic app.
Q1)
I am unable to control it on the new app āCanāt connect to device. Check device and try againā - Is this known or have I done something wrong? I cannot find the switch when scanning for new devices using the new app and I mainly use the new app so it would be nice to get it working here too.
Q2)
How do I now control the two switches in automations? Tapping on the device in the classic app I can clearly see the two switches but in automations there is only one.
Apologies if Iām asking Newby questionsā¦ Iāve just moved over to ST from HomeAssistant and think Iām struggling with how the ST forums are set up (for example, your DH is at the bottom of a thread for another DH which I suspect has been superseded?)
Thanks in advance.
Andy
I havenāt yet tried the DH on the new App as I tried the new App a few months ago and ended up with my whole system in a mess.
Smartthings has problems dealing with any device with more than one āendpointā, such as 2 switches. However, as mentioned in other comments on the forum, @erocm1231ās āVirtual Device Syncā works well in conjunction with this DH.
However, if you have configured the switch with one unwired switch it is better to use the āAdvanced Button Controllerā, ABC, to control button 1.
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Iāve made several significant changes since the version you are using, which had some features which could easily get the internal logic tied in knots.
The DH was never intended to be used with the single gang switch. I suspect the issue is trivial, but I donāt actually have a single gang switch to test it with.
Iāve just posted a version which works, sort of, in the new Samsung SmartThings App.
Iāve tested that it still works with @erocm1231ās āVirtual Device Syncā and with āAdvanced Button Controllerā.
I canāt find any documentation which explains how to organise the interface within the new App and I donāt know why it appears as it does. But it does work.
Now works with the new Samsung App
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If you are able to obtian logs when the on/off loop issue occurs then Iād be happy to look at them to see whether thereās something I can fix. Please switch on the ādebugā option.
Shall I close/lock this thread and aonghusmor open a dedicated thread for his DH?
This is to close the legacy issues and avoid confusion for people looking for DH for Aqara wired wall switches (W/o neutral).
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I agree. Now on Device Handler for Aqara 2 Gang Wired Wall Switch no Neutral
Iāll post some basic information later.
I cant lock the thread. But i have edited the first post to redirect to your new thread.
Thanks for your efforts to carry the torch onwards.
Hi @lpthanh
First of all thanks for your DHT. Itās working perfectly with Aqara Dual in Wall Relay (LLKZMK11LM) as well.
I have only one small issueā¦ status update in the modern ST app.
When I first started to use this DHT, if I click on one of the child devices (and sometimes on the main one), the on/off status wouldnāt update in both Classic & Modern apps.
I then disabled debug logging in the Classic app, this solved the issue there. But the modern App, I still have the same issue. The behaviour is that the button gets stuck with a spinning wheel, until I click on the device main icon, and go into its standalone page. Then the status updates & I can back out & the status is showing properly in the overview page. Same behaviour if I start from the button page, I need to back out & in again to force a ārefreshā of sorts.
Iām wondering if you figured out a way to resolve thisā¦
Otherwise perfectly working DHT. Thanks again.
I have just make it work with a DH that come with smartthings ide āZigbee Switchā it work very find with no problems
Interestingā¦ Did you make any changes to the DH or do you just use it āas isāā¦
Which output is controlled with this DH - L1 or L2?
I donāt make any change, the only error I belive I found is that I can only control l1 with s2
But in DH if you pair it with the smartthings classic app it create two separate devices like two separate switches and work with all functions.
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Hey, been using your DH for a while and the first switch has changed to this twice nowā¦ Any advice as Iām not sure whatās happened here?
Iām not able to action the switch while it looks like this and need to delete and reinstate the device
So the button with the circular arrow has disappeared. That is a situation I havenāt seen myself. Have you checked that nothing has changed in the settings? Tap the wheel symbol, upper right, check that everything is OK and then save. Iām mainly curious whether that āsaveā operation changes anything.