Problem join new device after update

What happened?

What happened?

I have an existing Zigbee2MQTT network with approximately 80 devices.

After updating Home Assistant / Zigbee2MQTT (and later updating the SLZB radio firmware while troubleshooting), the existing network continues to operate perfectly:

• All existing devices communicate normally.
• MQTT works.
• Coordinator is online.
• Permit Join returns OK.

However:

No new devices can ever join the existing network.

No interview starts.
No "device joined".
No "device announce".

Nothing appears in the Zigbee2MQTT log except the Permit Join confirmation.

---

Hardware

Coordinator:
SMLIGHT SLZB-06P7

Adapter:
zStack

Connection:
tcp://10.0.20.134:6638

Baud:
115200

---

Versions

Home Assistant:
2026.7.x

Zigbee2MQTT:
2.12.0-1

SLZB OS:
3.3.1 Stable

Radio firmware:
20260311
(previously 20240710)

---

Existing network

Channel:
15

PAN ID:
0x4FC2

Extended PAN ID:
BE7B08CB543BA2D6

Network key restored from coordinator_backup.json.

Approximately 80 devices.

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What I tested

✔ Updated radio firmware

✔ Coordinator <-> Router mode switch

✔ Restored Zigbee2MQTT backup

✔ Removed state.json

✔ Removed database.db

✔ Removed coordinator_backup.json

✔ Restored coordinator_backup.json

✔ Fresh database

✔ Fresh state

✔ Fresh configuration

✔ Multiple device manufacturers:

• IKEA
• Aqara
• Sonoff

None can join.

---

Important observation

I renamed the complete Zigbee2MQTT configuration directory and created a completely new Zigbee2MQTT instance.

Using:

• same coordinator
• same SLZB
• same radio
• same firmware
• same adapter
• same MQTT

Zigbee2MQTT created a NEW network.

Immediately afterwards:

An IKEA bulb joined successfully.

Interview completed successfully.

Therefore:

Hardware is confirmed working.

Radio is confirmed working.

Only the OLD Zigbee network refuses new joins.

---

coordinator_backup.json

Looks internally consistent.

PAN ID, Extended PAN ID and Network Key match the running network.

No duplicate IEEE addresses found.

---

Question

Could there be a zStack coordinator state (NVRAM/BDB/Trust Center state) that is not included in coordinator_backup.json and prevents new joins while existing devices continue to work?

Is there any known issue around commissioning existing zStack networks after updates?

What did you expect to happen?

No response

How to reproduce it (minimal and precise)

No response

Zigbee2MQTT version

2.12.0-1

Adapter firmware version

3.3.1 Stable

Adapter

SMLIGHT SLZB-06P7

Setup

Home Assistant:
2026.7.x
VM on Proxmox
Intel NUC 5gen

Device database.db entry

No response

Debug log

log.log

Notes

No response

Start by reviewing the attached log.log alongside coordinator_backup.json and the reported zStack, SLZB-06P7, and Zigbee2MQTT versions. Trace the existing-network commissioning and permit-join path, then determine whether the failure is reproducible and whether an omitted coordinator state explains why a fresh network accepts devices while the restored network does not.