Answer
This is caused by the SSH key-pair generation defaulting to a newer OpenSSH key format that the older connection code doesn't accept — the fix is to explicitly force the older PEM key format when the key pair is generated. In the utils folder (\\ifsremote\ifsroot\utils), back up and edit local.psm1, find the Add-KeybasedAuthWithLinuxBox function's ssh-keygen line, and add the -m PEM option to it (for example, changing ssh-keygen -b 2048 -t rsa -f "$prvKeyFile" -q -N "" to ssh-keygen -b 2048 -t rsa -m PEM -f "$prvKeyFile" -q -N ""). Save the file and rerun the KEY and KUBERNETES steps — this generates the key pair in the PEM format the connection code expects, avoiding the 'ssh-rsa is not supported' error that newer ssh-keygen defaults on some Windows versions (like 10) can trigger.