MongoDB Atlas won't connect from Vercel? Check the IP access list
Ship ItChecked against the official source
Source checked 10 Oct 2026 · Published 23 Oct 2026 · Last reviewed 23 Oct 2026 · By Ctrl+Z Therapy (how we test)
The short answer
MongoDB's docs: "Atlas only allows client connections to the cluster from entries in the project's IP access list". Your laptop's IP was probably added during setup, but your host's servers weren't. Vercel deployments use dynamic IP addresses, so MongoDB's Vercel integration page says the IP access list must allow all IP addresses (0.0.0.0/0).
What to do
- In Atlas, add your host's IP addresses to the project's IP access list. For Vercel, that means allowing all IP addresses (0.0.0.0/0). MongoDB's Vercel integration adds that entry for you.
- Our advice: use a strong database password, keep it in environment variables, and read Atlas's alert emails.
- Ask your AI tool: "My app can't reach MongoDB Atlas after deploying. Check the connection string, the database user, and tell me what to add to the Atlas IP access list for my host."
Good to know
- 0.0.0.0/0 means every address on the internet. When it's added, Atlas sends an alert email to the project's users.
- With the list open to all, your database username and password are what keep strangers out (our advice, not a MongoDB quote).
Source
- MongoDB: Atlas IP access list
- MongoDB: Troubleshoot connection issues
- MongoDB: Atlas and Vercel integration
Checked on 10 Oct 2026. Prices, limits and settings change, so check the source before you rely on them.