401?Your API key is missing, invalid or expired. Verify the Authorization: Bearer ... header and confirm the key is active in your dashboard.
Check whether the Base URL is correct, whether /v1 is required by the client and whether your local network can reach https://123api.co.
429 rate limit errors?Reduce request frequency, add retries with backoff and spread traffic across workers if you are sending bursts.
Query GET /v1/models first and use the exact model ID returned by your current account and environment.
When a third-party client reports vague connection errors, the fastest check is to run a direct curl test against https://123api.co/v1/chat/completions with the same key.