This was his solution, but it is not the most appropriate for this problem. This happens because versions higher than 6.3 mysql Workbench do not accept the extension .ppk ssh key.
In my case, I had problems with Workbench version 8.0.
The most suitable solution for this problem is to perform the ssh key conversion with the . ppk extension to the Openssh format.
To do so, open Puttygen > Conversions > Import Key > 'Select your key . ppk' > Export Openssh > Select your directory and save.
Use this ssh file, and run the test on the connection again that will work.
Remember that this is only possible if the ssh key is included in the "authorized_keys" file of the remote server.
Reference:
https://dev.mysql.com/doc/connector-net/en/connector-net-ssh-tunneling.html
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