When using Digital Ocean Droplets as Kubernetes Worker Nodes, there is no possibility of assigning the Reserved IP´s to the Droplets.

This is a Digital Ocean Reserved IP´s limitation described in:

When using external systems with whitelists tied to Droplets IP´s, every time they change either for a manual action or during the cluster upgrades (the most common scenario), the access to the external system is lost and a manual update of the whitelist must be done.

So, as this a very common scenario in production systems, it will be great to be added.