CentOS 7.9连接仅支持SSH v1的Cisco路由器时出现Connection reset错误的排查求助

各位大佬好，我现在碰到个麻烦事，想请大家帮忙支支招：我用的是CentOS 7.9.2009服务器，需要通过它连接一台仅支持SSH v1的Cisco路由器（路由器没法升级，这点已经确定了）。

我先做了这些操作：修改了/etc/ssh/ssh_config配置文件，把原本注释掉的#Protocol 2改成了Protocol 2,1，让客户端允许使用SSH v1协议。

但当我执行连接命令ssh test@10.180.20.1 -vvv时，连接直接被重置了，完整的debug日志如下：

OpenSSH_7.4p1, OpenSSL 1.0.2k-fips  26 Jan 2017
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 58: Applying options for *
debug2: resolving "10.180.20.1" port 22
debug2: ssh_connect_direct: needpriv 0
debug1: Connecting to 10.180.20.1 [10.180.20.1] port 22.
debug1: Connection established.
debug1: key_load_public: No such file or directory
debug1: identity file /home/audit/.ssh/identity type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/audit/.ssh/identity-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/audit/.ssh/id_rsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/audit/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/audit/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/audit/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/audit/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/audit/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/audit/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /home/audit/.ssh/id_ed25519-cert type -1
debug1: Remote protocol version 1.5, remote software version Cisco-1.25
debug1: match: Cisco-1.25 pat Cisco-1.* compat 0x60000000
debug1: Local version string SSH-1.5-OpenSSH_7.4
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to 10.180.20.1:22 as 'test'
debug1: Waiting for server public key.
Connection reset by 10.180.20.1 port 22

另外我也试过直接指定SSH v1版本连接，命令是ssh -v1 test@10.180.20.1 -vvv，结果还是同样的连接重置错误。

目前的情况是我没法直接操作那台Cisco路由器，只能在自己的CentOS机器上做测试，想问问大家有没有什么排查方向或者解决思路？提前感谢各位的帮助！

备注：内容来源于stack exchange，提问作者free