Create a NuGet proxy repository in Nexus Repo 3.22.0 with remote of:
Pull down the index page from the proxy:
Now set "Block outbound connections on the repository" in the proxy's configuration, save.
Invalidate the proxy's cache, and try to download the index page again:
This will fail with a 502 response.
Expected: If the remote is not available, the proxy repository should serve cached content.