The current architecture of Jenkins Health Advisor by CloudBees is relying on a server maintained and regularly update by the CloudBees Support team.

When an instance isn't connected to internet it cannot send a support bundle for being analysed automatically.

A solution not too much expensive could be to provide a front-end with a form where we ask the email to use and the support bundle to analyse (to be generated manually on the offline infrastructure).

Even if this is a server improvement, I am tracking it here on the plugin side to give the visibility to the community