We have a pipeline which builds applications in a windows server.

Problem

While it has been working normally, yesterday there started to have the
“received http code 403 from proxy after connect” error when trying to do git fetch on even Public repo and when accessing internal websites in our Jenkins pipeline.

Investigation

I checked that:

1. There is no proxy configured, because:
   1. In “Connections” tab and click on the “LAN settings” button. In
      the “Local Area Network (LAN) Settings” window, check if the “Use a proxy server for your LAN” checkbox is not ticked
2. There is no firewall for the windows server
3. The git credentials for sure work (because the same cred works on another server on same repo)

Behaviour

When I try to access the websites on internet explorer of the machine directly, it managed to access the website / git repo.

But in the script / when I try to run the command on cmd of the machine, there’s “received http code 403 from proxy after connect” error.

Attempts to solve the problem

I have searched for solutions online for a long time and tried many ways.
Such as:

1. Check if there’s git proxy configured / proxy configured -> no -> it typically means that the server is configured to directly access the internet without routing its traffic through a proxy server, right?
2. Tried to ping the website using cmd directly -> can ping

What is really confusing to me

What I don’t understand is that, if there’s no proxy / firewall & credentials work & there’s no network issue, why will there be “received http code 403 from proxy after connect” error?

Can you please advise what might be the issue / how should I debug it?

Thank you very much in advance.