You may wish to serve CRAN packages from your Package Manager server as described in the steps here: https://docs.posit.co/rspm/admin/getting-started/configuration/#quickstart-cran
However, you might be wondering which CRAN mirror is used when Package Manager synchronizes from a CRAN source.
Package Manager pulls CRAN packages and metadata from the Posit Package Service. Package Manager doesn't download packages directly from CRAN, Bioconductor, or PyPI. Instead, Posit maintains a curated S3 bucket that contains metadata about CRAN, Bioconductor, and PyPI, in addition to package tar files. The metadata is used to track day-to-day changes. More information about the Posit Package Service can be found in the administrator guide here.
If you still have issues after completing the above, you can always lodge a support ticket, where our group of friendly, and incredibly knowledgeable staff can assist with any issues that you may be having. You can submit a ticket here: