Hello, @demeo1988

No supported authentication methods available (server sent: publickey), it basically says that the server said it supported public key authentication only and PuTTY was not able to provide it. I will recommend you double-check the settings in PuTYY. You can check these tutorials:

https://docs.digitalocean.com/products/droplets/how-to/add-ssh-keys/create-with-putty/

https://www.digitalocean.com/community/tutorials/how-to-create-ssh-keys-with-putty-to-connect-to-a-vps

You can try copying the key via ssh instead of using PuTTY. You can also use the ssh-copy-id command in order to do so. An example will be:

ssh-copy-id -i ~/.ssh/mykey user@host

Hope that this helps!
Regards,
Alex

if you want to do this by windows cmd prompt please read the steps first before typing the cmds:

1.In windows cmd prompt: “ssh-keygen” (this will generate idrsa.pub and idrsa key for windows REMEMBER TO PRESS ENTER WHEN ASKES YOU PASSWORD IF YOU WANT TO SSH TO SERVER WITHOUT PASSWORD)

2.In windows cmd prompt: “scp [location of windows idrsa.pub] [linuxuser]@[linuxIP/linuxhostname]:~/.ssh/authorizedkeys” (this will copy windows pub key to linux server, the location of windows idrsa.pub is shown when you gave the cmd ssh-keygen)

https://linux.org/threads/solved-how-to-ssh-from-windows-to-linux-via-ssh-key.35120/#post-125914