There is no current resolution at this time. However, engineering is aware of this issue and working to fix the redirect.
Workaround:
As a workaround, edit the download link by changing port 9084 to 9087.
Example
Change
https://vcenter.domain.local:9084/vum-filedownload/download?file=SOFTWARE_SPEC_801009944.json
To
https://vcenter.domain.local:9087/vum-filedownload/download?file=SOFTWARE_SPEC_801009944.json