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Description

MongoDB Error 6, 'Host Unreachable', indicates that the client or server cannot establish a network connection to the specified target host. This error typically occurs when the host is offline, network paths are blocked, or the specified address is incorrect, preventing any communication.

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Error Message

Host Unreachable

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Known Causes

4 known causes

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Server Offline or Incorrect Address

The target MongoDB server or its host machine is powered off, not running, or the network address (IP/hostname) used for connection is incorrect.

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Firewall Blocking Connection

A firewall (either local on the server/client or network-level) is preventing communication on the MongoDB port (default 27017) or other necessary ports.

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Network Path Problems

Routing issues, DNS resolution failures, or other general network connectivity problems are preventing data packets from reaching the target host.

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MongoDB Service Inactive

The `mongod` or `mongos` process on the target host is not actively running, even if the host machine itself is online.

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Solutions

4 solutions available

1. Check Server is Running easy

Verify MongoDB server is up and accessible

1

Check server status

# Linux
systemctl status mongod

# macOS
brew services list | grep mongodb

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Start if stopped

sudo systemctl start mongod

2. Check Network Connectivity easy

Verify network path to server

1

Test connectivity

ping mongodb-server
telnet mongodb-server 27017

2

Check firewall

# Allow MongoDB port
sudo ufw allow 27017

3. Check Replica Set Availability medium

In replica set, check member status

1

Check replica set status

rs.status()

2

Connect to available member

mongosh "mongodb://primary:27017,secondary:27017/db?replicaSet=rs0"

4. Check DNS Resolution easy

Hostname might not resolve

1

Check DNS

nslookup mongodb-server

2

Use IP address instead

mongosh "mongodb://192.168.1.100:27017/db"

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Related Errors

5 related errors

MongoDB Error 6: Host Unreachable Connection Issue