Hi everyone,

I’m experiencing an issue with my FastAPI backend deployed on Vercel where outbound API calls to the Groq API intermittently fail with 503 Service Unavailable errors.

Details:

• The same API requests succeed 100% when made from my local development environment (status 200).
• When deployed on Vercel, the requests intermittently return 503 errors with the message: { "error": { "message": "Service Unavailable", "type": "internal_server_error" } }
• The request payload, headers, and API keys are consistent between local and deployed environments.
• This problem started occurring recently without any code changes on my side.
• I suspect the issue could be related to Vercel’s dynamic outbound IP ranges, rate limiting, or network restrictions.

Has anyone faced similar issues with outbound calls to third-party APIs? Are there known limitations on Vercel’s platform regarding external API connectivity? Any suggestions or recommended workarounds would be highly appreciated!

Thanks in advance!

— Pramod