[CERT-TEST-FAILURE] TC-CNET-4.29 fails at Step 8 — TH cannot re-discover the DUT on the PDC operational network after ConnectNetwork

Test Case

TC-CNET-4.29

Describe the bug

The test case TC_CNET_4_29 is validated using the recent TH image: v2.16-beta2+summer2026 , the test case fails at Step 8. The DUT joins the PDC network and completes EAP-TLS authentication successfully, but the TH is then unable to re-discover and reach the DUT on that network, and no CASE session is established.

• The DUT switches networks correctly and associates with TC-CNET-4.29-PDC-BD1D8F77 using WPA3-ENT-SHA256. EAP-TLS completes and the DUT publishes _matter._tcp on the new link.

• On the PDC link the DUT only obtains an IPv6 link-local address (fe80::a285:e3ff:feda:be18) — no IPv4 and no global IPv6 address is assigned.

• Step 8 then waits for the DUT to become reachable again. The TH never establishes a CASE session: from the DUT side, no Matter traffic at all is received for the entire ~2 minute window and the step fails.

The Wi-Fi fixture interface used for the PDC access point is wlx6ccdd6c589f0, while the SDK container selects wlan0 as its primary Wi-Fi interface.

Steps to reproduce the behavior:

1. Open the TH GUI.
2. Update the UI configuration as mentioned below:

"test_parameters": {
      "endpoint": 0
    }, network': {'wifi': { "ssid": "<SSID>", "password": "<wifi-password>",
            'interfaces': ['wlx6ccdd6c589f0'],
            'docker_image': 'ghcr.io/project-chip/csa-certification-tool-wifi:ed2832c'}}

3.Ensure the TC-CNET-4.29 test case is selected. 4.Make sure the DUT is advertising. (QA has used ESP32c6 as DUT) 5.Click the Start button on Test-Harness user interface.

Expected behavior

The test case should be run completely and PASS without any issues.

Platform

esp32

Anything else?

Failure Log files

TH GUI Controller log for reference:

• TC_CNET_4__29(CTRL).txt

DUT log for reference:

• TC_CNET_4_29(DUT).txt

Environment

Version: v2.16-beta2+summer2026 Sha: ed2832c