### Answer I don't have information about specific changes to Retell IP ranges or servers from the evening in my sources. However, there are a few things to check: Retell IP Allowlist For incoming requests to your Custom LLM WebSocket server, you should allowlist this Retell IP address:

100.20.5.228

[(1) ]() Status Page You can check for any outages or infrastructure issues. [(2) ]() Similar Issues Reported There have been previous instances of

error_llm_websocket_open

and related WebSocket connection issues that were caused by Retell-side outages which were subsequently fixed. Troubleshooting Steps - Verify your WebSocket endpoint is accessible and responding - Check that your server can accept connections from Retell's IP - If you enabled

auto_reconnect

in your config, ensure your server is responding to ping/pong events within the 2-second interval [(3) ]() I'd recommend checking the status page and reaching out to support if the issue persists.

​ To learn more, see the sources I considered: [[1] Setup WebSocket Server](https://docs.retellai.com/integrate-llm/setup-websocket-server) [[2] Looks like i'm not alone, but also getting intermittent call errors/websocket connection issues.](https://discord.com/channels/1186424376300679209/1455687138795327662) [[3] LLM WebSocket](https://docs.retellai.com/api-references/llm-websocket) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.