SSH on but unable to connect (says only sftp) [duplicate]
This message from ssh:
This service allows sftp connections only.
Connection to <host> closed.
is typical of this configuration in /etc/ssh/sshd_config on the server:
ForceCommand internal-sftp
Ordinarily, you use a ForceCommand only within a Match block, but without examining the actual configuration file, this is as far as I can predict.