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Putty is a very popular telnet client for windows, if instead of using ssh-keygen on bash, you plan on using putty as your SSH client. You'll need to convert your keys into OpenSSH format, this can be done using PuTTYgen. Simply load the private key into PuTTYgen, go to the Conversions menu, and select Export OpenSSH key. Then, save the private key file and perform the following steps to set up non-default keys with Azure DevOps server Git repositories. These steps should also be followed if you generate ssh keys using ssh-keygen, but don't save them to the default .ssh folder in your profile. 

The most important step, which is what gets overlooked the most, is that the keys must be in a folder that only you can read or edit. If the folder has wider permissions, SSH will not use the keys. Since these keys have not been generated using the standard process or saved in the default location, you'll need to make SSH aware of these keys. This can be done by running the following command which is used to start the ssh agent.

Now, your custom keys are ready to be used for connectivity with Git repositories in Azure DevOps Server.