CGNAT环境下通过DDNS服务器无法SSH访问的问题求助

我最近配置了No-IP的DDNS服务（已经完成DDNS设置和路由器端口转发），现在确实能连接到本地服务器，但不管是用SSH密钥还是密码都没法正常登录，折腾了好久都没解决，想请大家帮忙看看。

下面是我用ssh -v user@subdomain.sytes.net生成的调试日志：

OpenSSH_8.9p1 Ubuntu-3ubuntu0.1, OpenSSL 3.0.2 15 Mar 2022

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 subdomain.sytes.net [34.199.8.144] port 22.

debug1: Connection established.

debug1: identity file /home/user/.ssh/id_rsa type 0

debug1: identity file /home/user/.ssh/id_rsa-cert type -1

debug1: identity file /home/user/.ssh/id_ecdsa type -1

debug1: identity file /home/user/.ssh/id_ecdsa-cert type -1

debug1: identity file /home/user/.ssh/id_ecdsa_sk type -1

debug1: identity file /home/user/.ssh/id_ecdsa_sk-cert type -1

debug1: identity file /home/user/.ssh/id_ed25519 type -1

debug1: identity file /home/user/.ssh/id_ed25519-cert type -1

debug1: identity file /home/user/.ssh/id_ed25519_sk type -1

debug1: identity file /home/user/.ssh/id_ed25519_sk-cert type -1

debug1: identity file /home/user/.ssh/id_xmss type -1

debug1: identity file /home/user/.ssh/id_xmss-cert type -1

debug1: identity file /home/user/.ssh/id_dsa type -1

debug1: identity file /home/user/.ssh/id_dsa-cert type -1

debug1: Local version string SSH-2.0-OpenSSH_8.9p1 Ubuntu-3ubuntu0.1

debug1: Remote protocol version 2.0, remote software version OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.13

debug1: compat_banner: match: OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.13 pat OpenSSH_6.6.1* compat 0x04000002

debug1: Authenticating to subdomain.sytes.net:22 as 'user'

debug1: load_hostkeys: fopen /home/user/.ssh/known_hosts2: No such file or directory

debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts: No such file or directory

debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts2: No such file or directory

debug1: SSH2_MSG_KEXINIT sent

debug1: SSH2_MSG_KEXINIT received

debug1: kex: algorithm: curve25519-sha256@libssh.org

debug1: kex: host key algorithm: ssh-ed25519

debug1: kex: server->client cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none

debug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none

debug1: expecting SSH2_MSG_KEX_ECDH_REPLY

debug1: SSH2_MSG_KEX_ECDH_REPLY received

debug1: Server host key: ssh-ed25519 SHA256:<any_key>

debug1: load_hostkeys: fopen /home/user/.ssh/known_hosts2: No such file or directory

debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts: No such file or directory

debug1: load_hostkeys: fopen /etc/ssh/ssh_known_hosts2: No such file or directory

debug1: Host 'subdomain.sytes.net' is known and matches the ED25519 host key.

debug1: Found key in /home/user/.ssh/known_hosts:8

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: get_agent_identities: bound agent to hostkey

debug1: get_agent_identities: ssh_fetch_identitylist: agent contains no identities

debug1: Will attempt key: /home/user/.ssh/id_rsa RSA SHA256:<any_key>

debug1: Will attempt key: /home/user/.ssh/id_ecdsa

debug1: Will attempt key: /home/user/.ssh/id_ecdsa_sk

debug1: Will attempt key: /home/user/.ssh/id_ed25519

debug1: Will attempt key: /home/user/.ssh/id_ed25519_sk

debug1: Will attempt key: /home/user/.ssh/id_xmss

debug1: Will attempt key: /home/user/.ssh/id_dsa

debug1: SSH2_MSG_SERVICE_ACCEPT received

debug1: Authentications that can continue: publickey,keyboard-interactive

debug1: Next authentication method: publickey

debug1: Offering public key: /home/user/.ssh/id_rsa RSA SHA256:<any_key>

debug1: send_pubkey_test: no mutual signature algorithm

debug1: Trying private key: /home/user/.ssh/id_ecdsa

debug1: Trying private key: /home/user/.ssh/id_ecdsa_sk

debug1: Trying private key: /home/user/.ssh/id_ed25519

debug1: Trying private key: /home/user/.ssh/id_ed25519_sk

debug1: Trying private key: /home/user/.ssh/id_xmss

debug1: Trying private key: /home/user/.ssh/id_dsa

debug1: Next authentication method: keyboard-interactive

debug1: Authentications that can continue: publickey,keyboard-interactive

debug1: Authentications that can continue: publickey,keyboard-interactive

debug1: Authentications that can continue: publickey,keyboard-interactive

debug1: No more authentication methods to try.

user@subdomain.sytes.net: Permission denied (publickey,keyboard-interactive).

补充一下：我用本地IP从同一台电脑SSH访问服务器是完全正常的，公钥也已经正确存放在服务器的authorized_keys文件里了，之前试过一些网上的解决方案，但都没效果。

另外还有个情况，我用公网IP（路由器把9264端口转发到服务器的22端口）连接时，会直接卡住，下面是对应的调试日志：

$ ssh -v -p 9264 user@public.IP

OpenSSH_8.9p1 Ubuntu-3ubuntu0.1, OpenSSL 3.0.2 15 Mar 2022

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 public.IP [public.IP] port 9264.

debug1: Connection established.

debug1: identity file /home/user/.ssh/id_rsa type 0

debug1: identity file /home/user/.ssh/id_rsa-cert type -1

debug1: identity file /home/user/.ssh/id_ecdsa type -1

debug1: identity file /home/user/.ssh/id_ecdsa-cert type -1

debug1: identity file /home/user/.ssh/id_ecdsa_sk type -1

debug1: identity file /home/user/.ssh/id_ecdsa_sk-cert type -1

debug1: identity file /home/user/.ssh/id_ed25519 type -1

debug1: identity file /home/user/.ssh/id_ed25519-cert type -1

debug1: identity file /home/user/.ssh/id_ed25519_sk type -1

debug1: identity file /home/user/.ssh/id_ed25519_sk-cert type -1

debug1: identity file /home/user/.ssh/id_xmss type -1

debug1: identity file /home/user/.ssh/id_xmss-cert type -1

debug1: identity file /home/user/.ssh/id_dsa type -1

debug1: identity file /home/user/.ssh/id_dsa-cert type -1

debug1: Local version string SSH-2.0-OpenSSH_8.9p1 Ubuntu-3ubuntu0.1

备注：内容来源于stack exchange，提问作者nightcod3r