Really, you should because it would have prevent you this situation in the first place, but also some other future questions or problem you might have That's one of the few capital rules in XCP-ng world. Your master must ALWAYS be more recent than the slaves (or at the same level obviously), otherwise slaves won't be able to connect. I think you really need some assistance on best practices and such, please contact us so we can assist more generally. If this basic requirement is not understand, you might have other/deeper issues.