Server closed connection during identification exchange

[tsposato]

I'm hitting this issue seemingly with a specific SFTP Server I'm trying to connect to. However connecting to the same SFTP server via command line or using other clients like winscp work fine. When I put it into debug mode I don't see many extra logs but this is what I get:

2024-04-30 11:20:33.684  INFO 1 --- [    FM-AWS- 434] n.s.sshj.transport.random.JCERandom      : Creating new SecureRandom.
2024-04-30 11:20:33.684 DEBUG 1 --- [    FM-AWS- 434] n.s.sshj.transport.random.JCERandom      : Random creation took 0 ms
2024-04-30 11:20:33.685 DEBUG 1 --- [    FM-AWS- 434] net.schmizz.sshj.DefaultConfig           : Available cipher factories: [aes128-cbc, aes128-ctr, aes192-cbc, aes192-ctr, aes256-cbc, aes256-ctr, [email protected], [email protected], blowfish-cbc, blowfish-ctr, cast128-cbc, cast128-ctr, idea-cbc, idea-ctr, serpent128-cbc, serpent128-ctr, serpent192-cbc, serpent192-ctr, serpent256-cbc, serpent256-ctr, 3des-cbc, 3des-ctr, twofish128-cbc, twofish128-ctr, twofish192-cbc, twofish192-ctr, twofish256-cbc, twofish256-ctr, twofish-cbc, arcfour, arcfour128, arcfour256]
2024-04-30 11:20:33.852  INFO 1 --- [    FM-AWS- 434] n.schmizz.sshj.transport.TransportImpl   : Client identity string: SSH-2.0-SSHJ_0.31.0
2024-04-30 11:20:33.866 ERROR 1 --- [    FM-AWS- 434] n.schmizz.sshj.transport.TransportImpl   : Received end of connection, but no identification received.
2024-04-30 11:20:33.866 ERROR 1 --- [    FM-AWS- 434] c.f.h.s.i.CarrierFtpIntegration          : FTP integration was unsuccessful.
net.schmizz.sshj.transport.TransportException: Server closed connection during identification exchange at net.schmizz.sshj.transport.TransportImpl.init(TransportImpl.java:194) ~[sshj-0.31.0.jar:0.31.0]

This is what WinSCP tells me once successfully connected:

File transfer protocol = SFTP-6
Cryptographic protocol = SSH-2
SSH implementation = CerberusFTPServer_12.0
Encryption algorithm = AES-256 SDCTR (AES-NI accelerated)
Compression = No

When connecting via command line these are the logs:

[tsposato@linux ~]$ sftp -v user-In@server
OpenSSH_7.4p1, OpenSSL 1.0.2k-fips  26 Jan 2017
debug1: /etc/ssh/ssh_config line 58: Applying options for *
debug1: Connecting to server [1.2.3.4] port 22.
debug1: Connection established.
debug1: key_load_public: No such file or directory
debug1: identity file /home/user/.ssh/id_rsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/user/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/user/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/user/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/user/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/user/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/user/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/user/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_7.4
debug1: Remote protocol version 2.0, remote software version CerberusFTPServer_12.0
debug1: no match: CerberusFTPServer_12.0
debug1: Authenticating to server:22 as 'user-In'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: ecdh-sha2-nistp256
debug1: kex: host key algorithm: rsa-sha2-512
debug1: kex: server->client cipher: aes128-ctr MAC: hmac-sha2-256 compression: none
debug1: kex: client->server cipher: aes128-ctr MAC: hmac-sha2-256 compression: none
debug1: kex: ecdh-sha2-nistp256 need=32 dh_need=32
debug1: kex: ecdh-sha2-nistp256 need=32 dh_need=32
debug1: sending SSH2_MSG_KEX_ECDH_INIT
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ssh-rsa SHA256:FM9tGfSMPcQuDM1cmIUL9Ma1ypkUtZ6U2csFY43gf60
debug1: Host 'server' is known and matches the RSA host key.
debug1: Found key in /home/user/.ssh/known_hosts:21
debug1: rekey after 4294967296 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: rekey after 4294967296 blocks
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: password,publickey
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /home/user/.ssh/id_rsa
debug1: Authentications that can continue: password,publickey
debug1: Offering ECDSA public key: /home/user/.ssh/id_ecdsa
debug1: Authentications that can continue: password,publickey
debug1: Trying private key: /home/user/.ssh/id_rsa
debug1: Authentications that can continue: password,publickey
debug1: Trying private key: /home/user/.ssh/id_dsa
debug1: Trying private key: /home/user/.ssh/id_ecdsa
Enter passphrase for key '/home/user/.ssh/id_ecdsa':
debug1: Trying private key: /home/user/.ssh/id_ed25519
debug1: Next authentication method: password
user-In@server's password:
debug1: Authentication succeeded (password).
Authenticated to server ([1.2.3.4]:22).
debug1: channel 0: new [client-session]
debug1: Entering interactive session.
debug1: pledge: network
debug1: Sending environment.
debug1: Sending env LANG = en_US.UTF-8
debug1: Sending subsystem: sftp
Connected to server.
sftp> ls