OH THANK GOODNESS somebody else is reporting this! That timeline coincides with my troubles. I have 150+ TP link devices and I have done fresh installs TWICE because I’m so desperate for stability. I can look in the TP Link app and I can see the devices having rolling outages.
I have taken many steps to isolate this but all I have is theories.
First, I noticed the problems in the HA error logs starting a few months ago. Issues with devices losing connection (I never saw it in aggregate like you’re showing).
My roomate was convinced it was wifi interference because it was so intermittent. I tested against this by asking my neighbor to turn off his wifi for an entire day while I diagnosed the problem. I had the same instability when my neighbors wifi was off. I have ubiquiti with 7 access points.
Then I thought maybe it was something with my adaptive light add-on. I disabled all adaptive lighting integrations and the issue persisted.
Then, I noticed whenever my hub was off, I started regaining stability in the TP-link app (zero devices showing offline). It was reproduceable, whenever the hub was down, TP Link app seemed to recover. Restart hub, and everything will be stable for a little while and will eventually start degrading by throwing random devices offline.
I verified that there’s not a limit from TP link on how many devices the app can handle. Although I did find a weird quirk where you can’t have more than 37 devices in a group in tp link and that’s apparently new because my groups were created years ago. Thinking this might be a problem, I fixed all groups to under 37 devices. The issue persisted. I removed all devices in TP link and HA that aren’t currently online (halloween and christmas).
I got so frustrated that I ripped all TP link devices out of home assistant a few weeks ago and started to readd them. I experienced stability until I got over 100 devices and then I started witnessing the same symptoms again. And again, shutting down the hub achieves stability in the tp link app.
Now that I re-added all the devices, I thought maybe it’s struggling with polling 150+ devices. I went into all the bulbs and turned off polling because they’re programatically controlled. Physical switches require polling so they can detect when they’re turned on for auto-off countdowns. In the 25ish devices that have a physical switch, polling was left on. The issue persists.
I bought home assistant yellow today because I was so convinced there must be something that I can’t see/fix in my current system and I’m so desperate for stability. Like you, this stuff has been rock solid for years.