So we're in a position where we have to break the federation between our hosting server and Portal (10.9), because we are changing the federation url of our ArcGIS Server (therefore changing the url of the services endpoints). So we will break the federation, then refederate using the new ArcGIS Server urls (for example changing from gis.domain.com/arcgis to gis.domain.com/server)
I know this is not recommended or ideal but we're worked out with Esri tech support that is is necessary.
I don't quite understand what the implications are of an unfederation and refederation. I know what it will break all Portal items that point to REST urls will break. But what else?
Will any Portal items get deleted?
Will any ArcGIS Server services (hosted servers or Server services) get deleted?
On refederation will all services have associated items recreated in Portal, therefore duplicating those items, if the original items won't be deleted?
Will original Portal items lose their connection to the associated services, such that deleing those Portal items will not also delete the associated services?
What did you discover? We are about to do this to change FQDN on the new server set up.
Oooof - this was a while ago and somewhat annoying. In our case, we kept the same Portal URLs and just changed the Server context to /server from /arcgis. So we broke the federation, changed the server context, and refederated.
What happened was every service was republished, and created new Portal items for every Server service. This didn't pose a ton of problems with MapServices, utility services, etc. on Server - we just had to delete the old items from Portal referencing the old Server URLs. Also updating any content (feature layers, maps, etc. with new Server urls). However with hosted feature services from datastore, we lost the (hosted) or (hosted, view) labels in the content explorer, and it was a pain to fix (need to go into the Portal content directory and manually change some things in the json files). Survey123s and Workforce projects needed some additional remediation, since there are multiple types of linked assets created. I forget the details on that one because there was only a couple and some users were happy republishing their Surveys.
Hope that helps! Good luck!