Downloading application did not succeed error

Question

I have a wpf desktop application that I am trying to deploy with ClickOnce, which is failing on certain users computers but not others. For users with access to my network (those I work with) the app will auto update by looking at my build server for an updated version, but that server is behind a firewall and thus unreachable by users outside. When I provide the app to outside users they download/unzip/install with the application manifest. Some (but not all) outside user installs are unsuccessful with the following error:

ERROR DETAILS
Following errors were detected during this operation.
* [4/15/2022 2:18:00 PM] System.Deployment.Application.DeploymentDownloadException (Unknown subtype)

• Downloading https://my.build.server did not succeed.
• Source: System.Deployment
• Stack trace:
  at System.Deployment.Application.SystemNetDownloader.DownloadSingleFile(DownloadQueueItem next)
  at System.Deployment.Application.SystemNetDownloader.DownloadAllFiles()
  at System.Deployment.Application.FileDownloader.Download(SubscriptionState subState, X509Certificate2 clientCertificate)
  at System.Deployment.Application.DownloadManager.DownloadManifestAsRawFile(Uri& sourceUri, String targetPath, IDownloadNotification notification, DownloadOptions options, ServerInformation& serverInformation)
  at System.Deployment.Application.DownloadManager.DownloadDeploymentManifestDirect(SubscriptionStore subStore, Uri& sourceUri, TempFile& tempFile, IDownloadNotification notification, DownloadOptions options, ServerInformation& serverInformation)
  at System.Deployment.Application.DownloadManager.FollowDeploymentProviderUri(SubscriptionStore subStore, AssemblyManifest& deployment, Uri& sourceUri, TempFile& tempFile, IDownloadNotification notification, DownloadOptions options)
  at System.Deployment.Application.DownloadManager.DownloadDeploymentManifestBypass(SubscriptionStore subStore, Uri& sourceUri, TempFile& tempFile, SubscriptionState& subState, IDownloadNotification notification, DownloadOptions options)
  at System.Deployment.Application.ApplicationActivator.PerformDeploymentActivation(Uri activationUri, Boolean isShortcut, String textualSubId, String deploymentProviderUrlFromExtension, BrowserSettings browserSettings, String& errorPageUrl, Uri& deploymentUri)
  at System.Deployment.Application.ApplicationActivator.PerformDeploymentActivationWithRetry(Uri activationUri, Boolean isShortcut, String textualSubId, String deploymentProviderUrlFromExtension, BrowserSettings browserSettings, String& errorPageUrl)
  --- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
  at System.Deployment.Application.ApplicationActivator.PerformDeploymentActivationWithRetry(Uri activationUri, Boolean isShortcut, String textualSubId, String deploymentProviderUrlFromExtension, BrowserSettings browserSettings, String& errorPageUrl)
  at System.Deployment.Application.ApplicationActivator.ActivateDeploymentWorker(Object state)
  --- Inner Exception ---
  System.Net.WebException
• The remote name could not be resolved: 'my.build.server'
• Source: System
• Stack trace:
  at System.Net.HttpWebRequest.GetResponse()
  at System.Deployment.Application.SystemNetDownloader.DownloadSingleFile(DownloadQueueItem next)

Why is the installer trying to download from my build server on these users computers (and not other users) instead of just using the install files locally that came with the packaged ClickOnce deployment? When I install in this same manner, the installer shows me that it is "downloading" from the location of the deployment files which is local (i.e. my downloads dir). What is causing this difference among users?

Thanks for your help!