openssh. Problem with connection to servers via ssh

One of these days I faced the following problem. I needed to organize the ability to work on two computers with servers via ssh. On one machine a public and private key was generated, a config file was configured, everything worked well. Next, I copied the keys to another machine, also set up config file and verified that the key was added ($ ssh-add -l), but when I was trying to connect to any server I was failing. Both machines were on Ubuntu OS (17.10 and 16.04 LTS).
Next, I tried to test connection:

$ ssh -v your-useful.server.com

Output was next:

...
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

On the last line, the check was froze and ended after a while. After a short searching based on the last line of output, it turned out that problem was associated with a bug in the openssh package. The bug was revealed in the fact that each connection was required to refine the cipher via the -c key.

$ ssh -c aes256-ctr your-useful.server.com

After that, everything began to work. To exclude redundancy, you need to add either in /etc/ssh/ssh_config or in ~/.ssh/config (I chose this option) the following line:

Ciphers aes128-ctr,aes192-ctr,aes256-ctr