Winfoom proxy - Connection refused (os error 111)

To overcome the authentication required by our company proxy we are using Winfoom on dev machines. Unluckily Rancher Desktop gets no connection via Winfoom.

Error on moproxy.log is not very helpful.
proxies but failed: Connection refused (os error 111)

With protocol (HTTP vs HTTPS) is being used when connecting with proxy?

Any experiences using Winfoom? Are further debug logs available?