After upgarding to 2026.4.0 my Kasa power strip is disconnected. I get a prompt that says “Authentication expired” to put my login info again but it doesn’t work with the below error - the login info works fine on https://www.tplinkcloud.com/admin.php
“Unable to authenticate: Device response did not match our challenge on ip 192.168.86.29, check that your e-mail and password (both case-sensitive) are correct.”
I have in the past had a similar problem with their smart plugs Something to do with the fact that these devices share passwords between themselves. I had to turn off ALL the other devices then re-add the offending device. It then accepted the password. Embarrassingly it is mentioned in the installation instructions Hope this your problem as it is an easy fix.