Support cannot help either as you can see from the thread Remote access to DNS clients failed
You'll have to change all your update clients. But you used the wrong service anyway for what you're doing. DynDNS Pro is not supposed to be used in such a scenario. It is for private use only, exactly because it has no multiple logins, separate for each hostname.
If you can DM me or share here your ticket numbers I can follow up with support regarding them. I have added you as a friend, please accept so you can DM)
As Rotblitz shared Unfortunately once the password is changed from an older security protocol you must comply with the current for any future changes. If you can remote connect to their networks you can update the clients that way. Also using the updater client key will allow you to set up the devices on each site without needing to use the account password so if it is changed in the future this would not happen. The updater client key also is only used on the devices not logging into the account via account.dyn.com (but it would act as the password to all devices).
Oracle + Dyn