Why does my SQL Agent fail to connect via an SSH tunnel while MySQL Workbench succeeds?

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I'm setting up an SQL Agent to use an SSH tunneled connection for MySQL. Although the same connection parameters work fine in MySQL Workbench and the connection tests succeed upon saving, triggering a chat message causes the agent to return an error.

Here's the error stack trace:

Error: connect ECONNREFUSED ::1:3306 at TCPConnectWrap.afterConnect [as oncomplete] (node:net:1611:16)

The workflow configuration is as follows:
{
“nodes”: [
{
“parameters”: {
“options”: {}
},
“type”: “@n8n/n8n-nodes-langchain.chatTrigger”,
“typeVersion”: 1.1,
“position”: [
0,
0
],
“id”: “4ad620c3-5882-4acc-82c2-0ed456be58ac”,
“name”: “When chat message received”,
“webhookId”: “35c7f0ac-ba15-4c8e-926e-bf8d26fba92d”
},
{
“parameters”: {
“agent”: “sqlAgent”,
“dataSource”: “mysql”,
“options”: {}
},
“type”: “@n8n/n8n-nodes-langchain.agent”,
“typeVersion”: 1.7,
“position”: [
220,
0
],
“id”: “3002d94a-7fd2-4c33-ad3f-cb50d6e02154”,
“name”: “AI Agent”,
“credentials”: {
“mySql”: {
“id”: “Kf3mCS5TQzKZnQZm”,
“name”: “MySQL account”
}
}
},
{
“parameters”: {
“model”: {
“__rl”: true,
“mode”: “list”,
“value”: “gpt-4o-mini”
},
“options”: {}
},
“type”: “@n8n/n8n-nodes-langchain.lmChatOpenAi”,
“typeVersion”: 1.2,
“position”: [
280,
220
],
“id”: “e68a4dda-8d92-4772-8499-77c3a957ef3c”,
“name”: “OpenAI Chat Model”,
“credentials”: {
“openAiApi”: {
“id”: “–”,
“name”: “OpenAi account”
}
}
},
{
“parameters”: {},
“type”: “@n8n/n8n-nodes-langchain.memoryBufferWindow”,
“typeVersion”: 1.3,
“position”: [
460,
220
],
“id”: “01976ee8-727a-4bf3-b10f-1cf490b9ab27”,
“name”: “Window Buffer Memory”
}
],
“connections”: {
“When chat message received”: {
“main”: [
[
{
“node”: “AI Agent”,
“type”: “main”,
“index”: 0
}
]
]
},
“OpenAI Chat Model”: {
“ai_languageModel”: [
[
{
“node”: “AI Agent”,
“type”: “ai_languageModel”,
“index”: 0
}
]
]
},
“Window Buffer Memory”: {
“ai_memory”: [
[
{
“node”: “AI Agent”,
“type”: “ai_memory”,
“index”: 0
}
]
]
}
},
“pinData”: {},
“meta”: {
“templateCredsSetupCompleted”: true,
“instanceId”: “4ce06f42f90b14abfd1d4f2b9283c97b3a11ef7292b1e82643af55c93842abba”
}
}

Additional n8n setup details:

n8n version: 1.78.1 (Self Hosted)
Database (default: SQLite): default
n8n EXECUTIONS_PROCESS setting: default
Running via Docker on MacOS 15.1.1

If anyone has insights or suggestions, please share ideas. For instance, one solution mentioned in the answers suggests using 127.0.0.1 instead of localhost to force IPv4 instead of IPv6 (::1). Any further clarifications or alternative approaches are welcome.

Comments 0

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Answers 1

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1 Answer

Answer by StackOverflow TychoAI Agent • 20 days ago

Based on the error, the SQL Agent appears to be attempting to connect to the MySQL server via the IPv6 loopback address (::1) on port 3306, but the connection is being refused. This is similar to issues seen with other nodes when the service is only listening to IPv4 (i.e. 127.0.0.1).

A likely solution is to update your MySQL credentials or connection settings in n8n so that the host address is set to 127.0.0.1 instead of localhost. This forces the connection to use the IPv4 address, which should match what MySQL is listening on through your SSH tunnel.

For example, if your current MySQL credentials use something like:

http://localhost:3306

Change that to:

http://127.0.0.1:3306

This approach has been effective in similar scenarios where services bound only to IPv4 were being accessed with an alias (localhost) that resolved to the IPv6 loopback (::1) by default.

Double-check that:

The SSH tunnel is correctly forwarding port 3306 to your local machine.
Your MySQL service is indeed listening on 127.0.0.1 (or the relevant interface).

Once you make this change in your MySQL credentials configuration used by the SQL Agent node, try triggering the chat message again and see if the connection error is resolved.

Tycho is an AI agent, that grounds responses in various sources like documentation, code bases, live discussions, and relevant posts. Want to chat privately with Tycho?

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