Even after Sftp is turned off, the HuaWei switch cannot be connected, but both CRT and PuTTY do not have this problem

日志如下，麻烦大神帮忙分析一下，万分感激：
[20220409 12:04:39] ssh_connect: libssh 0.9.6 (c) 2003-2021 Aris Adamantiadis, Andreas Schneider and libssh contributors. Distributed under the LGPL, please refer to COPYING file for information about your rights, using threading threads_winlock
[20220409 12:04:39] getai: host 127.0.0.1 matches an IP address
[20220409 12:04:39] ssh_socket_connect: Nonblocking connection socket: 2924
[20220409 12:04:39] ssh_connect: Socket connecting, now waiting for the callbacks to work
[20220409 12:04:39] ssh_connect: Actual timeout : 10000
[20220409 12:04:39] ssh_socket_pollcallback: Poll callback on socket 2924 (POLLOUT ), out buffer 0
[20220409 12:04:39] ssh_socket_pollcallback: Received POLLOUT in connecting state
[20220409 12:04:39] socket_callback_connected: Socket connection callback: 1 (0)
[20220409 12:04:39] ssh_socket_unbuffered_write: Enabling POLLOUT for socket
[20220409 12:04:39] ssh_socket_pollcallback: Poll callback on socket 2924 (POLLOUT ), out buffer 0
[20220409 12:04:39] ssh_socket_pollcallback: Poll callback on socket 2924 (POLLIN ), out buffer 0
[20220409 12:04:39] callback_receive_banner: Received banner: SSH-2.0--
[20220409 12:04:39] ssh_client_connection_callback: SSH server banner: SSH-2.0--
[20220409 12:04:39] ssh_analyze_banner: Analyzing banner: SSH-2.0--
[20220409 12:04:39] ssh_client_select_hostkeys: Order of wanted host keys: "ssh-ed25519,ecdsa-sha2-nistp521,ecdsa-sha2-nistp384,ecdsa-sha2-nistp256,rsa-sha2-512,rsa-sha2-256,ssh-rsa,ssh-dss"
[20220409 12:04:39] ssh_known_hosts_read_entries: Failed to open the known_hosts file '/etc/ssh/ssh_known_hosts': No such file or directory
[20220409 12:04:39] ssh_client_select_hostkeys: No key found in known_hosts; changing host key method to "ssh-ed25519,ecdsa-sha2-nistp521,ecdsa-sha2-nistp384,ecdsa-sha2-nistp256,rsa-sha2-512,rsa-sha2-256,ssh-rsa,ssh-dss"
[20220409 12:04:39] ssh_log_hexdump: session cookie (16 bytes):
[20220409 12:04:39] ssh_log_hexdump: 00000000 a4 4b 63 a2 c4 a7 ea 79 8e 5e 15 fe 0a da c1 fe .Kc....y.^......
[20220409 12:04:39] ssh_list_kex: kex algos: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group18-sha512,diffie-hellman-group16-sha512,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1,ext-info-c
[20220409 12:04:39] ssh_list_kex: server host key algo: ssh-ed25519,ecdsa-sha2-nistp521,ecdsa-sha2-nistp384,ecdsa-sha2-nistp256,rsa-sha2-512,rsa-sha2-256,ssh-rsa,ssh-dss
[20220409 12:04:39] ssh_list_kex: encryption client->server: aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-ctr,aes256-cbc,aes192-cbc,aes128-cbc,blowfish-cbc,3des-cbc
[20220409 12:04:39] ssh_list_kex: encryption server->client: aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-ctr,aes256-cbc,aes192-cbc,aes128-cbc,blowfish-cbc,3des-cbc
[20220409 12:04:39] ssh_list_kex: mac algo client->server: hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,hmac-sha1-96-etm@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1,hmac-sha1-96
[20220409 12:04:39] ssh_list_kex: mac algo server->client: hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,hmac-sha1-96-etm@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1,hmac-sha1-96
[20220409 12:04:39] ssh_list_kex: compression algo client->server: none
[20220409 12:04:39] ssh_list_kex: compression algo server->client: none
[20220409 12:04:39] ssh_list_kex: languages client->server:
[20220409 12:04:39] ssh_list_kex: languages server->client:
[20220409 12:04:39] ssh_socket_unbuffered_write: Enabling POLLOUT for socket
[20220409 12:04:39] packet_send2: packet: wrote [type=20, len=1084, padding_size=8, comp=1075, payload=1075]
[20220409 12:04:39] ssh_send_kex: SSH_MSG_KEXINIT sent
[20220409 12:04:39] ssh_packet_socket_callback: rcv packet cb (len=568, state=INIT)
[20220409 12:04:39] ssh_packet_socket_callback: packet: read type 20 [len=564,padding=7,comp=556,payload=556]
[20220409 12:04:39] ssh_packet_incoming_filter: Filtering packet type 20
[20220409 12:04:39] ssh_packet_process: Dispatching handler for packet type 20
[20220409 12:04:39] ssh_log_hexdump: session cookie (16 bytes):
[20220409 12:04:39] ssh_log_hexdump: 00000000 e2 4e a4 a3 e7 3e 4d 47 59 dd 9a 63 f5 87 b8 0a .N...>MGY..c....
[20220409 12:04:39] ssh_list_kex: kex algos: diffie-hellman-group16-sha512,diffie-hellman-group15-sha512,diffie-hellman-group14-sha256,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1
[20220409 12:04:39] ssh_list_kex: server host key algo: ecdsa-sha2-nistp521,ssh-dss,ssh-rsa
[20220409 12:04:39] ssh_list_kex: encryption client->server: aes256-ctr,aes128-ctr,aes256-cbc,aes128-cbc,3des-cbc
[20220409 12:04:39] ssh_list_kex: encryption server->client: aes256-ctr,aes128-ctr,aes256-cbc,aes128-cbc,3des-cbc
[20220409 12:04:39] ssh_list_kex: mac algo client->server: hmac-sha2-256,hmac-sha2-256-96,hmac-sha1,hmac-sha1-96,hmac-md5,hmac-md5-96
[20220409 12:04:39] ssh_list_kex: mac algo server->client: hmac-sha2-256,hmac-sha2-256-96,hmac-sha1,hmac-sha1-96,hmac-md5,hmac-md5-96
[20220409 12:04:39] ssh_list_kex: compression algo client->server: none,zlib
[20220409 12:04:39] ssh_list_kex: compression algo server->client: none,zlib
[20220409 12:04:39] ssh_list_kex: languages client->server:
[20220409 12:04:39] ssh_list_kex: languages server->client:
[20220409 12:04:39] ssh_kex_select_methods: Negotiated diffie-hellman-group16-sha512,ecdsa-sha2-nistp521,aes256-ctr,aes256-ctr,hmac-sha2-256,hmac-sha2-256,none,none,,
[20220409 12:04:39] ssh_make_bignum_string: 4096 bits, 512 bytes, 1 padding

[20220409 12:04:39] packet_send2: packet: wrote [type=30, len=524, padding_size=5, comp=518, payload=518]
[20220409 12:04:39] ssh_packet_socket_callback: rcv packet cb (len=0, state=INIT)
[20220409 12:04:39] ssh_packet_socket_callback: Waiting for more data (0 < 8)
[20220409 12:04:39] ssh_socket_pollcallback: Poll callback on socket 2924 (POLLOUT ), out buffer 528
[20220409 12:04:39] ssh_socket_unbuffered_write: Enabling POLLOUT for socket
[20220409 12:04:39] ssh_socket_pollcallback: Poll callback on socket 2924 (POLLOUT ), out buffer 0
[20220409 12:04:39] ssh_socket_pollcallback: sending control flow event
[20220409 12:04:39] ssh_packet_socket_controlflow_callback: sending channel_write_wontblock callback
[20220409 12:04:49] ssh_connect: Timeout connecting to 10.48.254.111
[20220409 12:04:49] ssh_connect: current state : 9
[20220409 12:04:49] ssh_socket_unbuffered_write: Enabling POLLOUT for socket
[20220409 12:04:49] packet_send2: packet: wrote [type=1, len=28, padding_size=7, comp=20, payload=20]

Start with the supplied libssh 0.9.6 connection log and reproduce the Huawei switch timeout while SFTP is disabled, comparing it with CRT and PuTTY. Trace the SSH negotiation through the reported timeout and document a confirmed cause and reproducible fix, but the issue names no source files or tests to begin with.

Written by the indexing model from the issue text.