Z2M ENOTFOUND failures

255 · February 13, 2026, 11:50pm

My Z2M addon is frequently stopping and the logs indicate it is because it is unable to connect to my zigbee controller:

[2026-02-13 16:27:50] e[32minfoe[39m: 	z2m: Logging to console, file (filename: log.log)
[2026-02-13 16:27:50] e[32minfoe[39m: 	z2m: Starting Zigbee2MQTT version 2.8.0 (commit #unknown)
[2026-02-13 16:27:50] e[32minfoe[39m: 	z2m: Starting zigbee-herdsman (9.0.2)
[2026-02-13 16:27:50] e[32minfoe[39m: 	zh:zstack:znp: Opening TCP socket with slzb-06.internal:6638
[2026-02-13 16:27:50] e[31merrore[39m: 	zh:zstack:znp: Socket error Error: getaddrinfo ENOTFOUND slzb-06.internal
[2026-02-13 16:27:50] e[31merrore[39m: 	z2m: Error while starting zigbee-herdsman
[2026-02-13 16:27:50] e[31merrore[39m: 	z2m: Failed to start zigbee-herdsman
[2026-02-13 16:27:50] e[31merrore[39m: 	z2m: Check https://www.zigbee2mqtt.io/guide/installation/20_zigbee2mqtt-fails-to-start_crashes-runtime.html for possible solutions
[2026-02-13 16:27:50] e[31merrore[39m: 	z2m: Exiting...
[2026-02-13 16:27:50] e[31merrore[39m: 	z2m: Error: Error while opening socket

However, the host itself can resolve the SLZB-06 address just fine. Eg. from the HA CLI i drop into the host using ‘login’ and nslookup gives the SLZB-06 address just fine.

The host is a Home Assistant VM on a machine physically connected to the same switch the SLZB-06 controller is connected to (ie. by ethernet).

I’ve tried specifying the ip address of the SLZB-06 in my Z2M yaml, but I still get ENOTFOUND error. So, it doesn’t seem to be an issue with Z2M being able to resolve an ip address.

I’m a bit stumped as to why Z2M is unable to connect to the SLZB-06. It doesn’t seem to be a name resolution issue since I get the same issue when i specify the ip address, and the host itself has no issue resolving the address. Grateful for any thoughts/suggestsions.

Sir_Goodenough · February 14, 2026, 12:06am

Is it connected thru a switch that has a WIFI connection between the router and the switch. Like a Mesh by WIFI router?
might be a WIFI interruption. (intermittently)

255 · February 14, 2026, 12:33am

No, the machine that hosts the Home Assistant VM and the SLZB-06 are both connected to the same switch by ethernet. The Home Assistant VM itself has no problem resolving the SLZB-06 address and can ping the SLZB-06. I try and start Z2M add on and I get the ENOTFOUND errors (intermittently unfortunately).

255 · February 18, 2026, 3:47am

OK, I installed the ‘Ping’ integration and when Zigbee2MQTT goes down, the ping integration is unable to detect the SLZB-06 host:

However, when I ‘login’ from the Home Assistant CLI, the Home Assistant machine itself can ping the SLZB-06 just fine. The SLZB-06 is running just fine and I can access its web interface directly from a laptop.

So, the issue doesn’t appear to be a problem with either the SLZB-06 or with Zigbee2MQTT. It appears to be something about how Home Assistant’s internal networking works. I know Home Assistant uses containers but I don’t understand how networking works with these. Grateful for any insights.

I tried (and ruled out) other solutions such as enabling multithreading on the SLZB-06 as suggested here:

github.com/Koenkk/zigbee2mqtt

zh:zstack:znp: Socket error using SLZB-06 and tcp/ethernet

opened 11:17AM - 30 Sep 24 UTC

closed 10:55PM - 10 Dec 24 UTC

indexample

problem

### What happened? after starting the Zigbee2MQTT addon for HA, it starts an…d opens socket successfully. in log messages (INFO) indicate the successful start. usually within a few minutes, sometimes 30 minutes, it crashes happens with: - both with Zigbee2MQTT and Zigbee2MQTT Edge - port: both with hardcoded IP and local dns name below a snippet of the debug log. as you can see, it runs normally (first timestamp 13:04:39 about skipping discovery, then crashes 2 minutes later: ``` **[2024-09-30 13:04:39]** debug: z2m: Skipping discovery of 'sensor/0xa4c13878fc15b22e/linkquality/config', already discovered **[2024-09-30 13:06:50]** debug: zh:zstack:unpi:parser: <-- [254,35,68,129,0,0,0,0,253,197,1,1,0,160,0,12,214,156,0,0,15,8,33,10,1,0,32,80,226,255,32,55,228,255,32,0,253,197,29,113] [2024-09-30 13:06:50] debug: zh:zstack:unpi:parser: --- parseNext [254,35,68,129,0,0,0,0,253,197,1,1,0,160,0,12,214,156,0,0,15,8,33,10,1,0,32,80,226,255,32,55,228,255,32,0,253,197,29,113] [2024-09-30 13:06:50] debug: zh:zstack:unpi:parser: --> parsed 35 - 2 - 4 - 129 - [0,0,0,0,253,197,1,1,0,160,0,12,214,156,0,0,15,8,33,10,1,0,32,80,226,255,32,55,228,255,32,0,253,197,29] - 113 [2024-09-30 13:06:50] debug: zh:zstack:znp: AREQ: <-- AF - incomingMsg - {"groupid":0,"clusterid":0,"srcaddr":50685,"srcendpoint":1,"dstendpoint":1,"wasbroadcast":0,"linkquality":160,"securityuse":0,"timestamp":10278412,"transseqnumber":0,"len":15,"data":{"type":"Buffer","data":[8,33,10,1,0,32,80,226,255,32,55,228,255,32,0]}} [2024-09-30 13:06:50] debug: zh:controller: Received payload: clusterID=0, address=50685, groupID=0, endpoint=1, destinationEndpoint=1, wasBroadcast=false, linkQuality=160, frame={"header":{"frameControl":{"frameType":0,"manufacturerSpecific":false,"direction":1,"disableDefaultResponse":false,"reservedBits":0},"transactionSequenceNumber":33,"commandIdentifier":10},"payload":[{"attrId":1,"dataType":32,"attrData":80},{"attrId":65506,"dataType":32,"attrData":55},{"attrId":65508,"dataType":32,"attrData":0}],"command":{"ID":10,"name":"report","parameters":[{"name":"attrId","type":33},{"name":"dataType","type":32},{"name":"attrData","type":1000}]}} [2024-09-30 13:06:50] debug: zh:controller:endpoint: ZCL command 0xa4c138997ce5df3d/1 genBasic.defaultRsp({"cmdId":10,"statusCode":0}, {"timeout":10000,"disableResponse":false,"disableRecovery":false,"disableDefaultResponse":true,"direction":1,"reservedBits":0,"transactionSequenceNumber":33,"writeUndiv":false}) [2024-09-30 13:06:50] debug: zh:zstack: sendZclFrameToEndpointInternal 0xa4c138997ce5df3d:50685/1 (0,0,1) [2024-09-30 13:06:50] debug: zh:zstack:znp: SREQ: --> AF - dataRequest - {"dstaddr":50685,"destendpoint":1,"srcendpoint":1,"clusterid":0,"transid":2,"options":0,"radius":30,"len":5,"data":{"type":"Buffer","data":[24,33,11,10,0]}} [2024-09-30 13:06:50] debug: zh:zstack:unpi:writer: --> frame [254,15,36,1,253,197,1,1,0,0,2,0,30,5,24,33,11,10,0,51] [2024-09-30 13:06:50] debug: zh:zstack:unpi:parser: --- parseNext [] [2024-09-30 13:06:50] debug: z2m: Received Zigbee message from 'Kantoorlamp1', type 'attributeReport', cluster 'genBasic', data '{"65506":55,"65508":0,"appVersion":80}' from endpoint 1 with groupID 0 [2024-09-30 13:06:50] debug: zh:zstack:unpi:parser: <-- [254,1,100,1,0,100] [2024-09-30 13:06:50] debug: zh:zstack:unpi:parser: --- parseNext [254,1,100,1,0,100] [2024-09-30 13:06:50] debug: zh:zstack:unpi:parser: --> parsed 1 - 3 - 4 - 1 - [0] - 100 [2024-09-30 13:06:50] debug: zh:zstack:znp: SRSP: <-- AF - dataRequest - {"status":0} [2024-09-30 13:06:50] debug: zh:zstack:unpi:parser: --- parseNext [] [2024-09-30 13:06:50] debug: zh:zstack:unpi:parser: <-- [254,3,68,128,0,1,2,196] [2024-09-30 13:06:50] debug: zh:zstack:unpi:parser: --- parseNext [254,3,68,128,0,1,2,196] [2024-09-30 13:06:50] debug: zh:zstack:unpi:parser: --> parsed 3 - 2 - 4 - 128 - [0,1,2] - 196 [2024-09-30 13:06:50] debug: zh:zstack:znp: AREQ: <-- AF - dataConfirm - {"status":0,"endpoint":1,"transid":2} [2024-09-30 13:06:50] debug: zh:zstack:unpi:parser: --- parseNext [] **[2024-09-30 13:07:36] info: zh:zstack:znp: Socket error** [2024-09-30 13:07:36] info: zh:zstack:znp: Port closed [2024-09-30 13:07:36] debug: zh:controller: Adapter disconnected [2024-09-30 13:07:36] info: zh:zstack:znp: closing [2024-09-30 13:07:36] error: z2m: Adapter disconnected, stopping [2024-09-30 13:07:36] debug: z2m: Saving state to file /config/zigbee2mqtt/state.json [2024-09-30 13:07:36] info: z2m:mqtt: MQTT publish: topic 'zigbee2mqtt/bridge/state', payload '{"state":"offline"}' [2024-09-30 13:07:36] info: z2m: Disconnecting from MQTT server [2024-09-30 13:07:36] info: z2m: Stopping zigbee-herdsman... [2024-09-30 13:07:36] debug: zh:controller:database: Writing database to '/config/zigbee2mqtt/database.db' [2024-09-30 13:07:36] info: z2m: Stopped zigbee-herdsman [2024-09-30 13:07:36] info: z2m: Stopped Zigbee2MQTT WATCHDOG: Waiting 0.03333333333333333min before next start try. Starting Zigbee2MQTT with watchdog (2000,60000,300000,900000,1800000,3600000). [2024-09-30 13:07:38] info: z2m: Logging to console, file (filename: log.log) [2024-09-30 13:07:38] debug: z2m: Loaded state from file /config/zigbee2mqtt/state.json [2024-09-30 13:07:38] info: z2m: Starting Zigbee2MQTT version 1.40.1 (commit #unknown) [2024-09-30 13:07:38] info: z2m: Starting zigbee-herdsman (0.57.3) [2024-09-30 13:07:38] debug: z2m: Using zigbee-herdsman with settings: '"{\"network\":{\"panID\":27209,\"extendedPanID\":[221,141,6,80,38,137,160,61],\"channelList\":[11],\"networkKey\":\"HIDDEN\"},\"databasePath\":\"/config/zigbee2mqtt/database.db\",\"databaseBackupPath\":\"/config/zigbee2mqtt/database.db.backup\",\"backupPath\":\"/config/zigbee2mqtt/coordinator_backup.json\",\"serialPort\":{\"path\":\"tcp://zigbee2mqtt-slzb06.local:6638\",\"adapter\":\"zstack\"},\"adapter\":{\"concurrent\":null,\"delay\":null,\"disableLED\":false}}"' [2024-09-30 13:07:38] debug: zh:controller: Starting with options '{"network":{"networkKeyDistribute":false,"networkKey":"HIDDEN","panID":27209,"extendedPanID":[221,141,6,80,38,137,160,61],"channelList":[11]},"serialPort":{"path":"tcp://zigbee2mqtt-slzb06.local:6638","adapter":"zstack"},"adapter":{"disableLED":false,"concurrent":null,"delay":null},"databasePath":"/config/zigbee2mqtt/database.db","databaseBackupPath":"/config/zigbee2mqtt/database.db.backup","backupPath":"/config/zigbee2mqtt/coordinator_backup.json"}' [2024-09-30 13:07:38] info: zh:zstack:znp: Opening TCP socket with zigbee2mqtt-slzb06.local:6638 [2024-09-30 13:07:38] info: zh:zstack:znp: Socket error [2024-09-30 13:07:38] error: z2m: Error while starting zigbee-herdsman [2024-09-30 13:07:38] error: z2m: Failed to start zigbee [2024-09-30 13:07:38] error: z2m: Check https://www.zigbee2mqtt.io/guide/installation/20_zigbee2mqtt-fails-to-start.html for possible solutions [2024-09-30 13:07:38] error: z2m: Exiting... [2024-09-30 13:07:38] error: z2m: Error: Error while opening socket at Socket.<anonymous> (/app/node_modules/zigbee-herdsman/src/adapter/z-stack/znp/znp.ts:178:24) at Socket.emit (node:events:529:35) at emitErrorNT (node:internal/streams/destroy:151:8) at emitErrorCloseNT (node:internal/streams/destroy:116:3) at processTicksAndRejections (node:internal/process/task_queues:82:21) /app/node_modules/winston/node_modules/readable-stream/lib/_stream_writable.js:264 var er = new ERR_STREAM_WRITE_AFTER_END(); ^ Error: write after end at writeAfterEnd (/app/node_modules/winston/node_modules/readable-stream/lib/_stream_writable.js:264:12) at DerivedLogger.Writable.write (/app/node_modules/winston/node_modules/readable-stream/lib/_stream_writable.js:300:21) at DerivedLogger.log (/app/node_modules/winston/lib/winston/logger.js:231:12) at Logger.log (/app/lib/util/logger.ts:189:25) at Logger.info (/app/lib/util/logger.ts:202:14) at Znp.onPortClose (/app/node_modules/zigbee-herdsman/src/adapter/z-stack/znp/znp.ts:108:16) at Object.onceWrapper (node:events:632:26) at Socket.emit (node:events:517:28) at TCP.<anonymous> (node:net:350:12) ``` ### What did you expect to happen? the addon keeps running / not crash ### How to reproduce it (minimal and precise) run the addon for a few minutes ### Zigbee2MQTT version 1.40.1-1 ### Adapter firmware version 20240710 ### Adapter SLZB-06 - CC2652P core firmware version: v2.3.6 (latest stable) zigbee OTA firmware revision: 20240710 (latest stable) ### Setup addon on home assistant, intel nuc x64 Hassio ### Debug log [log (1).log](https://github.com/user-attachments/files/17188827/log.1.log) [log.log](https://github.com/user-attachments/files/17188828/log.log)

I have created an automation that runs every 5 minutes and attempts to start Zigbee2MQTT if it’s not running. This eventually works. For example, when Zigbee2MQTT last went down, the automation tried restarting it every 5 minutes for 45 minutes before it worked. Whatever the issue with networking is, it eventually self corrects.

255 · March 2, 2026, 5:45am

Following up in case it is of any use to anyone.

This has been a really annoying issue. All signs pointed to a problem with the Zigbee2MQTT addon (app). The Z2M logs showed lots of failed attempts to connect to the SLZB-06, apparently unable to resolve the address, but there were also various errors suggesting ‘connection reset’. This was suggesting a networking problem.

Checked my network and no problems apparent. I could ping the SLZB-06 OK from various machines on my network. I logged in to HA CLI (using ‘login’) command and I can ping the SLZB-06 OK from the HA (virtual) machine itself.

So I open a shell in the Zigbee2mqtt docker container itself and cannot ping the SLZB-06 from there. So, this suggested some sort of networking error within the Z2M docker container.

I created a HA automation that detects when Z2M goes down and restarts the ‘Core’ and ‘Zigbee’ on the SLZB-06. This worked to a degree but I would still have periods of up to several hours of attempted restarts of Z2M.

Eventually, I found a comment by Koenkk (author of the HA Z2M plugin/app?) on GitHub:

It could also be an issue of the coordinator itself, in the past I read people having these issues when opening the web page of the coordinator.

From the following thread:

github.com/zigbee2mqtt/hassio-zigbee2mqtt

z2m: Error: Error while opening socket

opened 02:44PM - 09 Oct 24 UTC

closed 12:58AM - 07 Dec 24 UTC

magiva

Stale

### Description of the issue addon wont start it Was running, i added the firs…t device and now it wont start ### Addon version 1.40.2-1 ### Platform Core 2024.10.1 Supervisor 2024.10.0 Operating System 13.1 Frontend 20241002.2 ### Logs of the issue (if applicable) [16:39:59] INFO: Preparing to start... [16:40:00] INFO: Socat not enabled [16:40:00] INFO: Starting Zigbee2MQTT... Starting Zigbee2MQTT without watchdog. [2024-10-09 16:40:02] info: z2m: Logging to console, file (filename: log.log) [2024-10-09 16:40:02] info: z2m: Starting Zigbee2MQTT version 1.40.2 (commit #unknown) [2024-10-09 16:40:02] info: z2m: Starting zigbee-herdsman (2.1.3) [2024-10-09 16:40:02] info: zh:zstack:znp: Opening TCP socket with slzb-06.local:6638 [2024-10-09 16:40:02] info: zh:zstack:znp: Socket connected [2024-10-09 16:40:02] info: zh:zstack:znp: Socket ready [2024-10-09 16:40:02] info: zh:zstack:znp: Writing CC2530/CC2531 skip bootloader payload [2024-10-09 16:40:02] info: zh:zstack:znp: Socket error [2024-10-09 16:40:02] error: z2m: Error while starting zigbee-herdsman [2024-10-09 16:40:02] error: z2m: Failed to start zigbee [2024-10-09 16:40:02] error: z2m: Check https://www.zigbee2mqtt.io/guide/installation/20_zigbee2mqtt-fails-to-start.html for possible solutions [2024-10-09 16:40:02] error: z2m: Exiting... [2024-10-09 16:40:02] error: z2m: Error: Error while opening socket at Socket.<anonymous> (/app/node_modules/zigbee-herdsman/src/adapter/z-stack/znp/znp.ts:166:24) at Socket.emit (node:events:529:35) at emitErrorNT (node:internal/streams/destroy:151:8) at emitErrorCloseNT (node:internal/streams/destroy:116:3) at processTicksAndRejections (node:internal/process/task_queues:82:21) /app/node_modules/winston/node_modules/readable-stream/lib/_stream_writable.js:264 var er = new ERR_STREAM_WRITE_AFTER_END(); ^ Error: write after end at writeAfterEnd (/app/node_modules/winston/node_modules/readable-stream/lib/_stream_writable.js:264:12) at DerivedLogger.Writable.write (/app/node_modules/winston/node_modules/readable-stream/lib/_stream_writable.js:300:21) at DerivedLogger.log (/app/node_modules/winston/lib/winston/logger.js:231:12) at Logger.log (/app/lib/util/logger.ts:198:25) at Logger.info (/app/lib/util/logger.ts:211:14) at Znp.onPortClose (/app/node_modules/zigbee-herdsman/src/adapter/z-stack/znp/znp.ts:96:16) at Object.onceWrapper (node:events:632:26) at Socket.emit (node:events:517:28) at TCP.<anonymous> (node:net:350:12)

Now, I had the SLZB-06 web interface permanently open on my laptop recently while trying to diagnose these issues. The SLZB-06 has an option under ‘security’ to disable its web server when a socket (from Z2M?) is open. I enabled this option and Z2M seems to have been much more stable for the last few days.

To get back in to the SLZB-06 web interface, I now need to stop Z2M on HA. I hope this works longer term.