The only way that you could change the Portal owning URL is to un-federate and re-federate. This is the URL that was used to create the federation. But, if you just want to change the service URL in the federation to allow the client to be able to pull the services with the new URL follow these steps. Access the Portal sharing endpoint=> login=> home=> portal=> self=> servers=> click on the federation and update the service URL to the new URL.
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