SSH
PuTTY "Unable to use key file (OpenSSH SSH-2 private key (new format))": convert to .ppk
PuTTY can't read OpenSSH private keys directly. Load the key in PuTTYgen, save it as .ppk, and point PuTTY to the new file. Or skip PuTTY: Windows 10 and 11 have OpenSSH built in and use the id_rsa key as it is.