Accès SSH Mutualisé différent selon d'où l'on vient ?

Bonjour,

J'essaie de me connecter en SSH à mon serveur mutualisé. J'ai créé un .ssh/config avec une clé qui fonctionne quand je l'utilise à partir de chez moi, mais qui ne fonctionne pas quand je l'utilise à partir d'un serveur hébergé chez O2Switch (il s'agit de backuper des infos hors site).

J'ajoute qu'à partir du même serveur O2Switch, je n'ai pas de problème pour me connecter à un VPS OVH avec la même procédure...:-)

A partir de chez moi :

bertrand@PC-Pro-Bertrand:~/tripleperformance$ ssh -v monserveur
OpenSSH_8.2p1 Ubuntu-4ubuntu0.2, OpenSSL 1.1.1f 31 Mar 2020
debug1: Reading configuration data /home/bertrand/.ssh/config
debug1: /home/bertrand/.ssh/config line 24: Applying options for monserveur
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: include /etc/ssh/ssh_config.d/*.conf matched no files
debug1: /etc/ssh/ssh_config line 21: Applying options for *
debug1: Connecting to ssh.cluster020.hosting.ovh.net [91.134.248.251] port 22.
debug1: Connection established.
debug1: identity file /home/bertrand/.ssh/ovh_ssh type 0
debug1: identity file /home/bertrand/.ssh/ovh_ssh-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.2p1 Ubuntu-4ubuntu0.2
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.4p1
debug1: match: OpenSSH_7.4p1 pat OpenSSH_7.0*,OpenSSH_7.1*,OpenSSH_7.2*,OpenSSH_7.3*,OpenSSH_7.4*,OpenSSH_7.5*,OpenSSH_7.6*,OpenSSH_7.7* compat 0x04000002
debug1: Authenticating to ssh.cluster020.hosting.ovh.net:22 as 'mon-compte'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ssh-ed25519
debug1: kex: server->client cipher: chacha20-poly1305@openssh.com MAC: compression: none
debug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ssh-ed25519 SHA256:xxxxxxxxxxxxxxxxxxxxxxxxxxxx
debug1: Host 'ssh.cluster020.hosting.ovh.net' is known and matches the ED25519 host key.
debug1: Found key in /home/bertrand/.ssh/known_hosts:11
debug1: rekey out after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: rekey in after 134217728 blocks
debug1: Will attempt key: /home/bertrand/.ssh/ovh_ssh RSA SHA256:xxxxxxxxxxxxxxxxxxxxxxxxxxxx explicit
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Offering public key: /home/bertrand/.ssh/ovh_ssh RSA SHA256:xxxxxxxxxxxxxxxxxxxxxxxxxxxx explicit
debug1: Server accepts key: /home/bertrand/.ssh/ovh_ssh RSA SHA256:xxxxxxxxxxxxxxxxxxxxxxxxxxxx explicit
debug1: Authentication succeeded (publickey).
Authenticated to ssh.cluster020.hosting.ovh.net ([91.134.248.251]:22).
debug1: channel 0: new [client-session]
debug1: Requesting no-more-sessions@openssh.com
debug1: Entering interactive session.
debug1: pledge: network
debug1: client_input_global_request: rtype hostkeys-00@openssh.com want_reply 0
debug1: Sending environment.
debug1: Sending env LANG = C.UTF-8
Welcome to OVH
mon-compte@ssh01.cluster020.gra.hosting.ovh.net (php/7.3/production/stable) ~ $

A partir d'un serveur chez O2Switch :

[wkgv-xxxx@gaz ~]$ ssh -v monserveur
OpenSSH_7.4p1, OpenSSL 1.0.2k-fips 26 Jan 2017
debug1: Reading configuration data /home/wkgv-xxxx/.ssh/config
debug1: /home/wkgv-xxxx/.ssh/config line 8: Applying options for monserveur
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 58: Applying options for *
debug1: Connecting to ssh.cluster020.hosting.ovh.net [91.134.248.251] port 22.
debug1: connect to address 91.134.248.251 port 22: Connection refused
ssh: connect to host ssh.cluster020.hosting.ovh.net port 22: Connection refused

Y a-t-il des restrictions sur l'accès SSH en mutualisé en fonction de là d'où on vient ?

Merci de votre aide !