MikeP wrote

@SimonC. Good job sticking with this, it must be frustrating!  I have the older HS100 & HS110 and neither seem to have the issue, so it's not a general problem.

Seems like it really can only be a few things - hardware, with the relay being allowed to turn off, or firmware/web message causing a quick internal relay reset.  It can't be a crash/restart because the plugs will then stay off, they don't return to the last state.

Looks like you've covered most everything in your testing, but I didn't see these mentioned so in case they help:

 

1) use MAC filtering so the plug can't connect to your router - see if it's IP/network related

2) use your firewall so it can't get access to the internet, to see whether it's something coming back from TP Link's servers.

 

If 1 fails it might put the focus on hardware/power.  If only 2 fails it's a rogue cloud command, block them from the internet might be a solution (but so much for remote access).

 

FWIW there was a problem a few years ago where the plugs would reboot only on some circuits in some users homes - I think it turned out to be related to a bad neutral - these were in Europe.

 

Good luck, keep at it!

@MikeP thanks for these suggestions! Since I am on the case for several weeks now, being myself IT engineer for nearly 20 years, I already tested somehow what you are suggesting. Here's what I've done and what are my conclusion, please note that everything of this as been gave to TP-LINK in details already.
 

First of all, just like you, I have plently of old (2-3 years old) HS105 units that are not affected by this issue at all, only the TP-Link units I purchased within last year (4x HS103 and 1x KP400) are affected.

Now, here's what I've done :

1 - I took an HS103, then powered it "dry" for an entire day, I mean without anything connected to it (no load) and the unit still reboot randomly as soon as it's online.

2 - I took an HS103 (not the same) and then I removed it from my account while it's online, so it performed a clean removal and factory reset. Then I kept the HS103 powered it up (without being connected to the Wi-Fi) with a LED desk lamp on it and while it's not connected to the internet, the HS103 ran for an entire day without a single issue. This specific test excluded any power related issue. Which would have been VERY surprising since my house is very recent and built according to the most recent electrical standards in North America (I am in Canada).

So this last test tend to confirm that the issue is due to a "rogue cloud command" as you indicated somehow coming from TP-Link infrastructure.

The very last test I am patiently waiting to perform is to try some brand new HS103 I've ordered yesterday from Amazon that I assume wont be the same HW revision as my 1 year old HS103 that are all HW 2.1 as I indicated before. If the brand new HS103 who will be possibily HW 3.xx are not affected, that could be a good lead for a solution, however one thing will still persist, is that the KP400, that is a pretty new product and who don't actually have a newer HW revision as the HW 2.0 that is also affected... so even if I found a potention solution for the HS103 (that would be to request a warranty replacement at TP-LINK), the problem with the KP400 will still persist...

Anyway, let's go one step at a time. However what I am deploring right now is that TP-Link techinical support kinda "cut the line" (by email) for over a week now. The last communication I had with them is that they wanted me to return all of my HS103 myself (and pay for the return shipping) to them and they wanted to send me some old (new but old) HS105 smart plugs in exchange. I really mad about this solution since this is not a real solution, first of all the HS105 is a depricated product for a while and now I have 4x HS103, but I will need several few more soon and then the HS105 are not sold in store anymore (for a while). Secondly asking me to pay myself for the return of my HS103 units after spending hours and days of hard labor performing these test for there engineer it OUTRAGEOUS. Moreover I verified with a local carrier and returning the HS103 to TP-Link (in Canada the postage fees are very high) would cost me around 25$, which is more expensive that the value of the products that I'm returning!

TP-Link wrote

@SimonC. 

Hi, for your case,  really sorry for the inconvenience and we would notify the local warranty office to take care of your case as soon as possible.

 

 And for the rest of the users, if possible, please help us check the following details:

1. Did you use the Homebridge to manage the home devices?

2. If the home router supported guest network, please connect the smart plug to guest Wi-Fi and check again whether the auto rebooting issue continues;

3. After resetting HS103 and KP400, then please do not set it up and leave it un-configured; would it automatically turn on and off again?

4. What is the model number of your home router by the way?

 

Thank you very much for your cooperation and support.

@TP-Link 

1. No, I don't use Homebridge or any other third party solution to manage my home devices

2. My home wireless network is a TP-Link Omada system and yes, I can create a guest network and do the test later.

3. No, as I indicated I already performed that test and the result is no, when the plug is unconfigured it does not reboot while they are offline

4. My home router is Bell Canada's Fibe HomeHub 3000, however remember the Wi-Fi is provided by TP-Link Omada, not the home router

@SimonC. Another person with same issue. It just started the last 2 days. I had 2 plugs from last year that never did it and I purchased a 4 pack a month ago for more Xmas light control. They all were perfect until 2 days ago. I did resets and unplugged for hours and nothing worked. Then I went to every device to reset again but this time I picked a different router / mesh network. Seemed to work for now. Yes I have two mesh networks. I have split house bandwidth demand over two different connections (that's a long story but I have two different hotspots running two networks. It lets my boys game and me stream. If I had all on one we run out of bandwidth).

I was using Orbi mesh and switched to Deco mesh. Is it a coincidence that working on TP branded mesh? 
 

So something has happened independent the hardware. My mesh is same firmware, the HS103 are exactly the same. TP-link broke something remotely that makes it not work. 

@Alias69 My problem is with an Orbi mesh network.  i tried all different kinds of settings on my network to no avail.  I can't keep them connected long enough to update firmware manually.

@TP-Link 

We are several users having the same kind of issues on lb120.

What is very strange is that it all happened recently... Was there a firmware update of some kind that broke something?

In our cases here : 

https://community.tp-link.com/en/smart-home/forum/topic/236580?replyId=533048

The smart light bulb randomly turns on/off after 2 years working smoothly. 

Is it related somehow? 

we already tried factory reset, de pairing/re pairing.... Nothing seems to work... At first the light bulb is correctly paired and working after some time it turns off by itself, sometimes it turns on randomly... Then again turns off... Last night I manage to turn it off, then at 3 o'clock during night time it turned on by itself... I had to cut the power off in the light bulb. 

Any thoughts from tp link please? 

@TP-Link my issue with hs-103 started few months ago and for all the plug and switch i own only the hs -103 are experiencing flashing. the problem start right out of the box when new. got an exchange from amazon and the new one same problem.used with tp-link router.

maxinike1 wrote

@TP-Link my issue with hs-103 started few months ago and for all the plug and switch i own only the hs -103 are experiencing flashing. the problem start right out of the box when new. got an exchange from amazon and the new one same problem.used with tp-link router.

@maxinike1 exactly like me.. I have many HS200 and HS105 and not have issues, but all my HS103 (6x) and my KP400 exterior smart plug are cutting ON/OFF continuously every few minutes or hours (variable).