Trouble deactivating Studio 2021 Freelance license

I am setting up a new PC and am in the process of migrating two Trados Studio versions from my old system to the new one: Studio 2024 Freelance and Studio 2021 Freelance. I had no problems with Studio 2024--I deactivated the license on my old system, installed Studio on my new one and activated the license there. Easy-peasy. With Studio 2021, however, I am unable to deactivate the app on my old system (I am told that the activation server cannot be reached.) I apparently cannot deactivate it from my RWS account either--my version 2021 license is not listed under Licenses & Subscriptions (only my most up-to-date version 2024 is). Granted, it's more important for me to be able to work in Studio 2024 Freelance, which, as I said, is no problem, but I have reasons for wanting to hang on to version 2021 as well. Any help would be welcome. Thank you!   

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