Issue with Litellm behind corporate proxy: Only certain provider settings work

[CookerPot]

Context

We're running Litellm behind a strict corporate proxy. The proxy allows outgoing traffic only to api.openai.com.

• With Provider set to OpenAI Text Completion (see screenshot 1), everything works and requests pass through the proxy without issues.
• With Provider set to OpenAI (see screenshot 2), the connection fails and requests do not pass through the proxy.
  • If I additionally set Mode to Completion - /completion for this model, it works again.

Questions

• Has anyone else encountered similar issues running Litellm behind a proxy, where only certain provider/mode settings work for OpenAI?
• Do you have any advice or workaround for this scenario?
• Where in the request flow could the problem be? Is Litellm trying to call other endpoints or domains in some modes, even when OpenAI is selected?
• What are the exact endpoint URLs that need to be allowed through the firewall for Litellm to work fully with OpenAI as the provider?
  At the moment, we only have api.openai.com allowed. Is there anything else required, or any non-standard endpoints that Litellm might use for health checks or other operations?

Screenshots

Screen 1 (working):

Screen 2 (not working unless Mode is set to Completion - /completion):


Screen 3 (working):

Any feedback or ideas appreciated. Thanks!