What are we Missing for Effective Remote Laboratories?

Remote laboratories play an important role in modern education. Because of this, a multitude of different protocols and systems for building and integrating remote laboratories have been developed over the last years. This Paper analyses these different protocols and systems (SCORM / xAPI, IMS-LTI, IEEE 1876-2019, IVI / VISA, OPC-UA, Weblab-Deusto / LabsLand, GOLDi-Labs) and sorts them into different layers to build a protocol stack for implementing remote laboratories, accompanied by some examples of what is currently possible to implement. A gap in the protocol stack was identified between Controller and the whole Laboratory where no standardised protocol exists. Suggestions for the requirements of such a protocol are laid out. The new possibilities with such a protocol are presented by showing examples of new types of remote laboratories, followed by a short discussion of problems not yet solved by such a new protocol.