Hmm
I am seeing the same problem. I have 4 smart plugs.
But it is not as bad as in your case. In my situation, the smart plugs are randomly offline.
On the apps, it appears as offline, but the smart plug has a green LEN on it.
In some cases, it stayed offline so I have to reset and reinstall it.
Imagine, if you are away from the site, how can one possible to reset and reinstall it remotely.
The apps mydlink Home version is 3.0.7
The smart plug firmware version 1.24
I talked with the DLink tech Support and they said they have not seen it before. They asked for further information and I have forwarded to them.
The problem is the smart plug is disconnecting and reconnecting every few minutes with the router.
I have a Dlink 890Router (unfortunately) and a log server to record all the log message from the router.
According to the log file, I can see the smart plug acquire new client connection from router every few minutes.
You may try to record the router log into a file and check on it.
If you can return the plug, then return it.
As in my case, my plugs warranty will expires soon. And i do not foreseen getting a RMA before the warranty expires.
When the warranty expires, I will stuck with them.
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