SSH / SFTP wont work anymore after Server update

Hi,

We are using Cilkat since many years, after SSH server update on a embedded machine, we are no more able to connect ( ActiveX with VBS ) this one. It did look like the Chilkat SSH client isnt able to find a agreement about the cypher to be used with the old chilkat version. I updated the Chilkat software - since then we still have failures - but they changed >> see log below. Looks like finding a agreement on encryption/MAC/compression took place ... but then at the end we find a timeout

sshDhGex: Socket operation timeout. Failed to read KEX_DH_GEX_REQUEST response

Any idea welcome - thx Michael

Connect_SFtp:
    DllDate: Mar 11 2016
    ChilkatVersion: 9.5.0.56
    UnlockPrefix: xxxxxxxxxxx  /not public    
    Username: xxxxxxxxxx  /not public
    Architecture: Little Endian; 32-bit
    Language: ActiveX
    VerboseLogging: 1
    SftpVersion: 0
    connectInner:
        hostname: 172.21.88.21
        port: 22
        sshConnect:
            connectSocket:
                domainOrIpAddress: 172.21.88.21
                port: 22
                connectTimeoutMs: 10000
                connect_ipv6_or_ipv4:
                    This is an IPV4 numeric address.
                    Domain to IP address resolution not needed.
                    getAddressInfo:
                        (leaveContext)
                    connecting to IPV4 address...
                    ipAddress: 172.21.88.21
                    createSocket:
                        Setting SO_SNDBUF size
                        sendBufSize: 262144
                        Setting SO_RCVBUF size
                        recvBufSize: 4194304
                        (leaveContext)
                    connect:
                        Waiting for the connect to complete...
                        ck_getsockname_ipv4:
                            (leaveContext)
                        myIP: 172.21.45.1
                        myPort: 4644
                        socket connect successful.
                        (leaveContext 16ms)
                    (leaveContext 32ms)
                (leaveContext 32ms)
            Established TCP/IP connection with SSH server
            Turning on TCP_NODELAY.
            (leaveContext 32ms)
        sshSetupConnection:
            clientIdentifier: SSH-2.0-PuTTY_Release_0.66
            Sending client identifier...
            Done sending client identifier.
            Reading server version...
            initialDataFromSshServer: SSH-2.0-unknown

serverVersion: SSH-2.0-unknown
            build_kexInit:
                preferRsaHostKeyAlgorithm: 1
                (leaveContext)
            sendMessageInOnePacket:
                (leaveContext)
            KeyExchangeAlgs:
                algorithm: curve25519-sha256@libssh.org
                algorithm: ecdh-sha2-nistp256
                algorithm: ecdh-sha2-nistp384
                algorithm: ecdh-sha2-nistp521
                algorithm: diffie-hellman-group-exchange-sha256
                algorithm: diffie-hellman-group14-sha1
                (leaveContext)
            HostKeyAlgs:
                algorithm: ssh-rsa
                (leaveContext)
            EncCS:
                algorithm: chacha20-poly1305@openssh.com
                algorithm: aes128-ctr
                algorithm: aes192-ctr
                algorithm: aes256-ctr
                algorithm: aes128-gcm@openssh.com
                algorithm: aes256-gcm@openssh.com
                (leaveContext)
            EncSC:
                algorithm: chacha20-poly1305@openssh.com
                algorithm: aes128-ctr
                algorithm: aes192-ctr
                algorithm: aes256-ctr
                algorithm: aes128-gcm@openssh.com
                algorithm: aes256-gcm@openssh.com
                (leaveContext)
            MacCS:
                algorithm: umac-64-etm@openssh.com
                algorithm: umac-128-etm@openssh.com
                algorithm: hmac-sha2-256-etm@openssh.com
                algorithm: hmac-sha2-512-etm@openssh.com
                algorithm: hmac-sha1-etm@openssh.com
                algorithm: umac-64@openssh.com
                algorithm: umac-128@openssh.com
                algorithm: hmac-sha2-256
                algorithm: hmac-sha2-512
                algorithm: hmac-sha1
                (leaveContext 16ms)
            MacSC:
                algorithm: umac-64-etm@openssh.com
                algorithm: umac-128-etm@openssh.com
                algorithm: hmac-sha2-256-etm@openssh.com
                algorithm: hmac-sha2-512-etm@openssh.com
                algorithm: hmac-sha1-etm@openssh.com
                algorithm: umac-64@openssh.com
                algorithm: umac-128@openssh.com
                algorithm: hmac-sha2-256
                algorithm: hmac-sha2-512
                algorithm: hmac-sha1
                (leaveContext)
            CompCS:
                algorithm: none
                algorithm: zlib@openssh.com
                (leaveContext)
            CompSC:
                algorithm: none
                algorithm: zlib@openssh.com
                (leaveContext)
            LangCS:
                (leaveContext)
            LangSC:
                (leaveContext)
            ChosenIncomingEncryption: aes256-ctr
            ChosenOutgoingEncryptoin: aes256-ctr
            ChosenIncomingMac: hmac-sha2-256
            ChosenOutgoingMac: hmac-sha2-256
            ChosenIncomingCompression: zlib@openssh.com
            ChosenOutgoingCompression: zlib@openssh.com
            ChosenKexAlgorithm: diffie-hellman-group-exchange-sha256
            choose_hostkey_algorithm:
                preferRsaHostKeyAlgorithm: 1
                (leaveContext)
            ChosenHostKeyAlgorithm: ssh-rsa
            numBits: 256
            pbits: 4096
            Using GEX Group.
            Sending KEX_DH_GEX_REQUEST...
            pbits: 4096
            sendMessageInOnePacket:
                (leaveContext 16ms)
            Failed to read 1st block_size bytes..
            sshDhGex: Socket operation timeout.
            Failed to read KEX_DH_GEX_REQUEST response
            (leaveContext 31047ms)
        (leaveContext 31094ms)
    Failed.
    (leaveContext 31109ms)
IsConnected:
    DllDate: Mar 11 2016
    ChilkatVersion: 9.5.0.56
    UnlockPrefix: xxxxxxxxxxx  /not public 
    Username: xxxxxxxxxxx  /not public 
    Architecture: Little Endian; 32-bit
    Language: ActiveX
    VerboseLogging: 1
    SftpVersion: 0
    (leaveContext)