Why a plant floor cannot be patched like an office

Production environments are not offices. The equipment is older, the tolerance for downtime is close to zero, and the people who run it are measured on output rather than patch levels.

That does not make them unfixable. It makes the order of operations different: understand what is actually on the network first, agree what may never stop, and work outwards from there.

Start with an inventory. You cannot protect what nobody has written down.