Description

I have multiple TP-Link Kasa HS200 switches on the same LAN. Some older HS200 switches work locally with python-kasa, while several newer HS200 switches fail during KLAP authentication.

The failing switches are controllable from the Kasa/Tapo app and through SmartThings, but they cannot be controlled locally by python-kasa or Home Assistant's TP-Link integration.

Environment

• python-kasa version: 0.10.2
• Python version: 3.12
• Host environment: Home Assistant OS SSH add-on on Raspberry Pi 4
• Home Assistant Core: 2026.5.3
• Network: same subnet, direct IP access works, devices respond to ping

Working Device

This HS200 works locally without credentials:

Model: HS200(US)
Host: 192.168.1.14
Port: 9999
Hardware: 5.0
Firmware: 1.0.11 Build 230908 Rel.160526
Mic Type: IOT.SMARTPLUGSWITCH
Credentials hash: None

Command:

kasa --host 192.168.1.14 --verbose state

Result: succeeds.

Failing Devices

Several HS200 devices fail, including:

HS200 at 192.168.1.234
Other affected HS200s: 192.168.1.74, 192.168.1.36, 192.168.1.124, 192.168.1.137

Command without credentials:

kasa --host 192.168.1.234 --verbose state

Result:

Raised error: Device response did not match our challenge on ip 192.168.1.234, check that your e-mail and password (both case-sensitive) are correct.
kasa.exceptions.AuthenticationError: Device response did not match our challenge on ip 192.168.1.234

Command with TP-Link credentials:

kasa --host 192.168.1.234 --username '<redacted>' --password '<redacted>' --verbose state

Result: same challenge mismatch.

Forcing legacy protocol:

kasa --host 192.168.1.234 --type plug --verbose state

Result:

Unable to connect to the device: 192.168.1.234:9999: [Errno 111] Connect call failed

So the failing devices are not available through the legacy port 9999 path.

Expected Behavior

python-kasa should authenticate to the newer HS200 devices using the supplied TP-Link/Kasa/Tapo credentials, or report a more specific unsupported protocol / firmware / credential-sync condition if this hardware revision is not supported.

Actual Behavior

The device is discovered/reached, but KLAP authentication fails with:

Device response did not match our challenge

The same credentials work in the Kasa/Tapo app, and the device works through SmartThings cloud integration.

Notes

This seems distinct from older no-auth HS200 local control. In my environment, older HS200 hardware/firmware still works locally on port 9999, while newer HS200 devices use port 80/KLAP and fail authentication.

I originally investigated this from Home Assistant, but direct python-kasa CLI testing reproduces the issue without Home Assistant involved.