Kex error when I connect via ssh remotely on Windows

Question

I am trying to use the in-built ssh server/client on windows10:
ssh opens just fine when i run ssh localhost or ssh user@local_IP_address (i am using key based authentication)

Now i've port forwarded port 22 in my router and am trying to access ssh via an external IP -

ssh user@remote_IP_address

i get

kex protocol error: type 30 seq 1

when i run

ssh user@remote_IP_address -vv

i get

OpenSSH_for_Windows_7.6p1, LibreSSL 2.6.4
debug2: resolving "domain" port 22
debug2: ssh_connect_direct: needpriv 0
debug1: Connecting to domain [domain] port 22.
debug1: Connection established.
debug1: identity file C:\Users\Asus/.ssh/id_rsa type 0
debug1: key_load_public: No such file or directory
debug1: identity file C:\Users\Asus/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file C:\Users\Asus/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file C:\Users\Asus/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file C:\Users\Asus/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file C:\Users\Asus/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file C:\Users\Asus/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file C:\Users\Asus/.ssh/id_ed25519-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_for_Windows_7.6
debug1: Remote protocol version 2.0, remote software version OpenSSH_for_Windows_7.6
debug1: match: OpenSSH_for_Windows_7.6 pat OpenSSH* compat 0x04000000
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to domain as 'asus'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug2: local client KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,ext-info-c
debug2: host key algorithms: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr
debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr
debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none
debug2: compression stoc: none
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug2: peer server KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,ext-info-c
debug2: host key algorithms: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ssh-ed25519-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr
debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr
debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none
debug2: compression stoc: none
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ecdsa-sha2-nistp256-cert-v01@openssh.com
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
kex protocol error: type 30 seq 1
debug1: Received SSH2_MSG_UNIMPLEMENTED for 1

I've tried using putty to connect and i get a similar error even when i re-arrange the kex algorithms so Diffie-Hellman group 1 is last

the error message says

Received unexpected packet when expecting ECDH reply,type 30(SSH2_MSG_KEX_ECDH_INIT)

Answer 1

There are rare cases mostly with virtual machines when putty as a SSH conexión interface fails due Microsoft security essentials or windows firewall to have solution that has to be configured, however regarding the type error string: Kex protocol error: type 30 seq 1 The error supposedly is defined by Diffie-Hellman group exchange KEX is absolete so has to be updated on both client And server for SSH usage additionally some putty terminals as software have to be updated. The following information can help: http://forum.filezila-project.org/viewtopic.php?t=37469 https://github.com/michaellukashov/Far-NetBox/issues/156