MongoDB Atlas connection timeout in Node.js Express despite IP whitelisting and DNS fixes
I am facing a MongoDB Atlas connection timeout issue in my Node.js + Express application.
Environment
- Node.js v24 (also tested with v22)
- Mongoose v9+ (also tested with v8.6)
- MongoDB Atlas
- VPS server (IPv4)
- Express.js backend
Problem
My application is unable to connect to MongoDB Atlas and always throws a timeout/server selection error.
Example error:
MongooseServerSelectionError: Could not connect to any servers in your MongoDB Atlas cluster
What I already tried
- IP Whitelisting
- Added my VPS public IP in MongoDB Atlas Network Access
- Also tried:
0.0.0.0/0
(still same issue)
- Different Connection Strings
Tried both:
- "mongodb+srv://"
- Standard connection string from Atlas
Still getting timeout issue.
- DNS Changes
Added public DNS servers:
- "8.8.8.8"
- "1.1.1.1"
Also tried:
require('dns').setDefaultResultOrder('ipv4first');
No change.
- Version Downgrade
Downgraded:
- Node.js 24 → 22
- Mongoose 9 → 8.6
Issue still persists.
- Network Testing
When testing connectivity from the VPS, the MongoDB domain connection also times out.
Question
What else should I check?
Could this be:
- VPS firewall issue?
- ISP/VPS provider blocking MongoDB Atlas ports?
- DNS/SRV resolution problem?
- MongoDB Atlas networking issue?
Has anyone faced a similar issue with MongoDB Atlas on a VPS?
Any debugging steps or fixes would help.