@Jethro65 Yup. I have the same issue.

I currently have 7 of the KL400's which have been purchased over the course of about a year from both Amazon and local retailers (All in Canada, for reference). EVERY.SINGLE.UNIT experiences the same issue as described here. They'll just drop out of the Kasa App (and HomeAssistant). Same error messages. 

If I wait a couple minutes it'll return to connectivity (sometimes), but if you remove the power and then reconnect it, they'll return almost immediately. This leads me to believe there's a memory leak or a process is hanging within the device/firmware.

I've reported it to TP-Link support and all I keep getting told is that it must be a problem with my WiFi, I should try changing channels, there's too much WiFi interference in my area, blah blah blah. It's all deflection and it's a joke. Somehow I have a hard time believing that's the case when no other devices drop out (including other TPLink devices), and they drop out at complete random. It's (extremely rarely) the same device twice in a row, and I'm going to have heavy doubts my WiFi coverage is an issue seeing as I'm running 2 x Ubiquiti U6-Lite APs in a 700sq ft condo.

Long story short, until TP-Link updates the firmware on these things, it's going to keep happening. Sadly, these are some of the best bang-for-your-buck devices out there which are WiFi controllable, colour changing, and have a great API and not some BS "home life" brand.

  @Paul_Michael Exactly, this is definitely a software bug on the devices. I started another thread for this: https://community.tp-link.com/us/smart-home/forum/topic/585662?replyId=1143138. It might be a good idea to create another bug/discussion for this to bring it to their attention.

I use them with Home Assistant and that is how I came to find out about the problem.

  @Riley_S This isn't helpful. Installing a beta version of the Kasa app isn't addressing the problem at all.

The problem is with the devices, not the app itself. We are using these devices through other means such as HomeAssistant and so-forth. Let me give more context.

- Install device (physically)

- Setup in Kasa app, and it successfully adds

- Add the device in HomeAssistant, etc

- Device will function for a period of time

- Suddenly it'll become unavailable in both the Kasa app and HomeAssistant

- Sometimes it'll come back online with no intervention, other times it requires a full power off/on

- When it's unresponsive, the button on the KL400 itself is sometimes not even responsive!

This tells me that there's a bug in the firmware of the little controller of the KL400 itself. This has nothing to do with the Kasa app.

I have been doing a ton of digging on this matter and found a few VERY interesting things which led me to a solution. For the tech people, I basically did some port mirroring and fired up wireshark to see what I'd see. When you use the Kasa app, there's a call from the app out to the WAN and then there's further traffic going to the device itself telling me that it somehow connects to a TPLink/Kasa server somewhere out there - it's not direct over the LAN communication. However, when you trigger an event through HomeAssistant the call goes directly from HomeAssistant to the device itself via API and not requiring the WAN.

So, I blocked off WAN access to the devices themselves to see if I could still trigger with HA and it worked. I've got all my home-automation stuff in it's own separate VLAN which is restricted from talking to anything else in the house for security purposes - I definitely don't trust some of these firmwares, nor the manufacturers. You should probably be doing this too, on a side note. Anyways, I then stuck all the KL400's in a range of IPs outside the DHCP scope through IP reservations, and blocked that small subnet from any sort of WAN access. This also resulted in all the devices no longer showing as online in the Kasa app, rendering it more or less useless besides adding new devices (which will then need to be pushed into that small subnet from my router). I've tested this by toggling the KL400's literally hundreds of times over the course of a couple minutes and there hasn't been a single failure. In fact, I'd suggest they're actually snappier to respond, it's quite literally instantly where-as through the app it's a short delay - further supporting my findings with how these things communicate through the WAN.

Just to confirm, I unblocked the devices from WAN access, tossed a bunch of triggers at them, and of course they locked up into an "unavailable" state yet again after a couple triggers. I should add, they also become "unavailable" in HomeAssistant too - which leads me to believe they just simply stop responding because of some bug in it's firmware. This has nothing to do with the app or HomeAssistant. Maybe the new "beta" app they suggested allows local LAN communication, but that's still not addressing the root problem of the firmware. This isn't even a patch, as the problem would persist when I'm triggering these things through the app when not on my local LAN, so I'm asking again for TP-Link to look at resolving the firmware issue. 

A WORKAROUND FOR THOSE INTERESTED

Basically, you block WAN access to the devices and control them over an API. If you are ONLY using the KASA app, and not another controller such as HomeAssistant, SmartThings, Hubitat or whatever, this ISN'T going to work for you. Anyways, here's the steps to complete it for a user that may not be super savvy.

1. Login to your router and check the DHCP scope. It'll probably be 192.168.1.100 - 192.168.1.199 or something. Basically you want to ensure there's at least a good handful of IPs in the subnet (which is 1-255) that ARE NOT in the scope. Remember what they are.

2. Go to your DHCP leases table (or something like that), note down the IP addresses and MACs of the KL400's you're using. 

3. Probably somewhere in the DHCP settings, you'll have somewhere you can "reserve an IP address by MAC". You want to then set all your KL400's to one of the IPs NOT in your DHCP scope (ideally). I'd keep them all together, such as .210, .211, .212, etc.. 

4. Probably under firewall, or security, or something like that, you'll be able to "block" WAN (or Internet) access to those devices.

5. Done.

Each router will be different, and some basic home routers may not be able to complete all these steps easily (if at all). If you're using the router supplied by your ISP, it's going to be hit and miss. Most Linksys, TP-Link and similar SOHO routers will allow these things. Pro and Enterprise grade routers will absolutely, and if you've got one of those, you're probably not reading this far in anyways because you already know what you're doing.

Anyways, there's absolutely some sort of bug in the firmware of the devices themselves.

TPLINK - Having your engineers focus on the Kasa app is a complete waste of time. They need to look at the devices themselves. Tell them to read this post.

  @Riley_S This is not the problem. I have the disconnects from Home Assitant and even from my own Python monitoring script connecting locally. This has nothign to do with my phone app. 

  @Paul_Michael @Riley_S It worked! Thanks for debugging this and providing a work around! Just block internet access on those LED strip devices and control via Home Assistant.

@Antonio253   - Cheers!

@Riley_S - It's kind of frustrating having your clients literally diagnosing problems that your engineers should have been able to sniff out in the initial testing of the device. That tells me that hey never put these through proper QA testing. Sad.

When they got these reports, you'd think they would have done more testing to replicate the problem, then sniffed out traffic, not just send out a beta version of the app. It means they didn't even listen to the problem, or they're simply incompetent when it comes to troubleshooting and are just throwing things at a wall to see what will stick. They're literally guessing. Part of the troubleshooting process is to test, replicate, diagnose source, fix problem, test, confirm. They absolutely didn't do this.

I look forward to TP-Link reaching out to me to send me some products for testing and review for all of my efforts here. 

Thank you for the work on diagnosis and the workaround, @Paul_Michael. Blocking WAN access to the light strip resolved my issues with lag, unresponsiveness, and "Became unavailable" in home assistant.

@Riley_S I have other Kasa smart devices (HS105s, HS220s, HS200s) which haven't run into any issues that I'm experiencing with the KL400L5. It doesn't seem to be app related.

  @Jethro65 Same here. I have four (4) of the KL400L5 strips and I am experiencing the same issue.  Firmware version on all of them is 1.0.8, no issues connecting to WiFi hotspot (less than 10 feet away), but I get drops, reconnects, etc. constantly when using the app.  I eventually unplug/replug the power adapter and then thigs will work for a while but a day or so later will drop again.  VERY glitchy.  I have 40 different Kasa/tp-link products, from switches, plugs, lights - all work perfectly EXCEPT these LED strips I just added.

Suggestions from support?

  @MK13654 See detailed response from @Paul_Michael above.