@dean-houston
By way of follow up, unfortunately the verbose output of an apt update against the jenkins repo provided exactly 0 clarity.

apt update -o Debug::Acquire::http=true
Ign:1 https://pkg.jenkins.io/debian-stable binary/ InRelease
Hit:2 https://pkg.jenkins.io/debian-stable binary/ Release
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
All packages are up to date.

I appreciate the help in trying to make this work, but I am going to punt on this and just grant the specific server access directly to pkg.jenkins.io.

@stevedennis That is where I am having the trouble, I believe the connector is setup correctly (unless I am misunderstanding).

For reference here is the currently working artifactory setup:

My primary use case for ProGet is to replace artifactory as an ubuntu repository proxy. Most ubuntu machines do not need direct access to the web, and thus would update packages via ProGet. I am having a particular issue when attempting to proxy the debian-stable repo for Jenkins specifically. No matter how I set my connector URL, distribution, and component I get a 404:

Local index file update failure: The remote server returned an error: (404) Not Found.

System.Net.WebException: The remote server returned an error: (404) Not Found.
   at System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
   at System.Threading.Tasks.TaskFactory`1.FromAsyncCoreLogic(IAsyncResult iar, Func`2 endFunction, Action`1 endAction, Task`1 promise, Boolean requiresSynchronization)
--- End of stack trace from previous location ---
   at System.Net.WebRequest.GetResponseAsync()
   at Inedo.ProGet.GlobalExtensions.GetResponseAsync(HttpWebRequest request, CancellationToken cancellationToken)
   at Inedo.ProGet.Feeds.Connector.GetDirectResponseAsync(String url, CancellationToken cancellationToken)
   at Inedo.ProGet.Feeds.Connector.GetCachedResponseAsync(String url, CancellationToken cancellationToken)
   at Inedo.ProGet.Feeds.Connector.GetCachedTextReaderAsync(String url, Boolean bufferEntireResponse, CancellationToken cancellationToken)
   at Inedo.ProGet.Feeds.Debian2.Debian2Connector.UpdateIndexAsync(Debian2ConnectorIndex localIndex)
   at Inedo.ProGet.Feeds.Debian2.Debian2Connector.Inedo.ProGet.Feeds.ILocalIndexFileConnector.UpdateIndexAsync(CancellationToken cancellationToken)
   at Inedo.ProGet.Feeds.CachedIndexFileMan.UpdateConnectorIndexAsync(Int32 connectorId, CancellationToken cancellationToken)

::Connector Error on 2/19/2026 5:22:07 PM::

This might be a redirect on the Jenkins side, but I have just not been able to get this to work.
https://pkg.jenkins.io/debian-stable binary

If my apt file is setup to the above directly, it works fine. My artifactory repo is set to use https://pkg.jenkins.io/ and it works fine. I cannot get ProGet connector to connect.

Am I missing something obvious?