Too many authentication failures for xxx

[dverbern]

I am using VShell 4.4.3 (x64 build 1966) on a Windows Server 2008 R2 x64 host. One of the connections to a 3rd party we engage in via SFTP using VShell is failing, giving the following error in logs:

"RECV: Disconnect packet (reason: 2: A protocol error occurred. Too many authentication failures for XXX )"

Where XXX is the username we're using to authenticate with the external party.

Parts of the log I think are relevant are:

Selected Kex Method = ecdh-sha2-nistp521
Selected Host Key Algo = ssh-dss
Selected Send Cipher = aes256-ctr
Selected Recv Cipher = aes256-ctr
Selected Send Mac = hmac-sha2-512
Selected Recv Mac = hmac-sha2-512
Authenticating as user XXX
RECV : USERAUTH_FAILURE, continuations [publickey,password]
Using agent for key store.
Loaded next key from store: SUCCEEDED
SENT : USERAUTH_REQUEST [publickey (ssh-dss) - unsigned,agent,fingerprint (SHA-2 hash): e7:03:a8:a3:ec:a7:e6:8a:58:a5:4b:53:c7:38:5c:b8:96:25:d3:f1:0a:57:52:d6:63:7f:b8:90:bf:5c:0c:ad]
SENT : USERAUTH_REQUEST [publickey (ssh-dss) - unsigned,agent,fingerprint (SHA-1 hash): 6e:67:46:36:96:40:7d:10:08:f6:77:18:71:5b:2e:31:d9:a4:e9:5c]
SENT : USERAUTH_REQUEST [publickey (ssh-dss) - unsigned,agent,fingerprint (MD5 hash): a7:a6:ae:a9:ed:c1:23:66:52:f8:58:4d:16:4b:e3:e4]
RECV : USERAUTH_FAILURE, continuations [publickey,password]
Loaded next key from store: SUCCEEDED
SENT : USERAUTH_REQUEST [publickey (ssh-rsa) - unsigned,agent,fingerprint (SHA-2 hash): fb:d7:17:ed:ad:40:62:c8:e3:de:3b:63:ec:77:5c:91:9f:57:72:e6:34:39:5e:cc:0f:2b:c6:68:65:21:8a:cc]
SENT : USERAUTH_REQUEST [publickey (ssh-rsa) - unsigned,agent,fingerprint (SHA-1 hash): 52:b5:f8:b8:a2:88:1f:9d:0e:11:61:cd:e6:fc:8a:e2:69:69:b2:d7]
SENT : USERAUTH_REQUEST [publickey (ssh-rsa) - unsigned,agent,fingerprint (MD5 hash): 7a:68:93:6b:d5:ff:d1:f6:c9:6e:53:28:5e:75:2b:73]
RECV : USERAUTH_FAILURE, continuations [publickey,password]
Loaded next key from store: SUCCEEDED
SENT : USERAUTH_REQUEST [publickey (ssh-rsa) - unsigned,agent,fingerprint (SHA-2 hash): 4d:cf:49:cc:7a:e5:7d:62:af:83:34:e0:c6:78:29:6e:6f:f7:f0:54:72:63:75:61:73:14:27:6a:42:a1:af:58]
SENT : USERAUTH_REQUEST [publickey (ssh-rsa) - unsigned,agent,fingerprint (SHA-1 hash): 82:7e:38:9c:d5:aa:24:70:5c:1a:98:f8:e0:cb:32:c7:82:74:a9:06]
SENT : USERAUTH_REQUEST [publickey (ssh-rsa) - unsigned,agent,fingerprint (MD5 hash): c6:34:12:75:7b:de:fa:27:88:75:da:51:92:63:0e:a2]
RECV : USERAUTH_FAILURE, continuations [publickey,password]
Loaded next key from store: FAILED
Using agent for key store.
Loaded next key from store: SUCCEEDED
SENT : USERAUTH_REQUEST [publickey (ssh-dss) - unsigned,agent,fingerprint (SHA-2 hash): e7:03:a8:a3:ec:a7:e6:8a:58:a5:4b:53:c7:38:5c:b8:96:25:d3:f1:0a:57:52:d6:63:7f:b8:90:bf:5c:0c:ad]
SENT : USERAUTH_REQUEST [publickey (ssh-dss) - unsigned,agent,fingerprint (SHA-1 hash): 6e:67:46:36:96:40:7d:10:08:f6:77:18:71:5b:2e:31:d9:a4:e9:5c]
SENT : USERAUTH_REQUEST [publickey (ssh-dss) - unsigned,agent,fingerprint (MD5 hash): a7:a6:ae:a9:ed:c1:23:66:52:f8:58:4d:16:4b:e3:e4]
RECV : USERAUTH_FAILURE, continuations [publickey,password]
Loaded next key from store: SUCCEEDED
SENT : USERAUTH_REQUEST [publickey (ssh-rsa) - unsigned,agent,fingerprint (SHA-2 hash): fb:d7:17:ed:ad:40:62:c8:e3:de:3b:63:ec:77:5c:91:9f:57:72:e6:34:39:5e:cc:0f:2b:c6:68:65:21:8a:cc]
SENT : USERAUTH_REQUEST [publickey (ssh-rsa) - unsigned,agent,fingerprint (SHA-1 hash): 52:b5:f8:b8:a2:88:1f:9d:0e:11:61:cd:e6:fc:8a:e2:69:69:b2:d7]
SENT : USERAUTH_REQUEST [publickey (ssh-rsa) - unsigned,agent,fingerprint (MD5 hash): 7a:68:93:6b:d5:ff:d1:f6:c9:6e:53:28:5e:75:2b:73]
RECV : USERAUTH_FAILURE, continuations [publickey,password]
Loaded next key from store: SUCCEEDED
SENT : USERAUTH_REQUEST [publickey (ssh-rsa) - unsigned,agent,fingerprint (SHA-2 hash): 4d:cf:49:cc:7a:e5:7d:62:af:83:34:e0:c6:78:29:6e:6f:f7:f0:54:72:63:75:61:73:14:27:6a:42:a1:af:58]
SENT : USERAUTH_REQUEST [publickey (ssh-rsa) - unsigned,agent,fingerprint (SHA-1 hash): 82:7e:38:9c:d5:aa:24:70:5c:1a:98:f8:e0:cb:32:c7:82:74:a9:06]
SENT : USERAUTH_REQUEST [publickey (ssh-rsa) - unsigned,agent,fingerprint (MD5 hash): c6:34:12:75:7b:de:fa:27:88:75:da:51:92:63:0e:a2]
Changing state from STATE_CONNECTION to STATE_CLOSING
RECV: Disconnect packet (reason: 2: A protocol error occurred. Too many authentication failures for XXX )
Changing state from STATE_CLOSING to STATE_CLOSED

It seems to me that my end is trawling through too many identity files(?) before reaching some sort of set limit and then bombing the whole authentication.

We DID indeed upgrade to newer VShell version recently, with the attendant changes in default algorithms and so forth, so I'm assuming that's lead directly to this.

Any assistance to resolve this much appreciated. This is the only 3rd party we are currently unable to connect to post VShell update.