This problem is usually solved as follows:
enter
1. cd /etc/ssh
2.vim /etc/ssh/sshd_config

# Add the following to the configuration file (except the last one of the third is gray plus purple, the others are blue, if it is gray means it is not right!)
Ciphers aes128-cbc,aes192-cbc,aes256-cbc,aes128-ctr,aes192-ctr,aes256-ctr,3des-cbc,arcfour128,arcfour256,arcfour,blowfish-cbc,cast128-cbc
 
MACs hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,hmac-sha1-96,hmac-md5-96
 
KexAlgorithms diffie-hellman-group1-sha1,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group-exchange-sha256,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group1-sha1,[email protected]

Then restart sshd with this statement and you’re done
systemctl restart sshd

Because the error page can not be selected, so I did not directly check the error, but with their own understanding of the error to check, but wasted a lot of time, so if such an error, or hand typing in the future, it is very fast.