Cannot ssh/deploy anything to Ubuntu server - ruby-on-rails

Question

I tried to log in/deploy something to a Ubuntu server is my Rails app, but suddenly this morning I ma unable to log in there.
When I run the SSH ssh deployer#IP -p 420 and enter the password, I get a message that the password is incorrect and the message Permission denied, please try again.
When I try to deploy some code with Capistrano, I get:
connection failed for: IP (Net::SSH::AuthenticationFailed: deployer)
Password is, again, correct.
This issue occurred today, yesterday was everything working perfectly.
I double checked the Capistrano set up, but everything is correctly set up there.
How to inspect the issue? Where to start? It simply looks like today it stopped working.
EDIT:
ssh -v XXX.XXX.XXX.XX
OpenSSH_6.9p1, LibreSSL 2.1.7
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 21: Applying options for *
debug1: Connecting to XXX.XXX.XXX.XX [107.170.160.89] port 22.
debug1: connect to address XXX.XXX.XXX.XX port 22: Connection refused
ssh: connect to host XXX.XXX.XXX.XX port 22: Connection refused
EDIT2:
ssh adam$ ssh -v XXX.XXX.XXX.XX -p 420
OpenSSH_6.9p1, LibreSSL 2.1.7
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 21: Applying options for *
debug1: Connecting to XXX.XXX.XXX.XX [XXX.XXX.XXX.XX] port 420.
debug1: Connection established.
debug1: identity file /Users/adam/.ssh/id_rsa type 1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/adam/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/adam/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/adam/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/adam/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/adam/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/adam/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/adam/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_6.9
debug1: Remote protocol version 2.0, remote software version OpenSSH_6.0p1 Debian-3ubuntu1
debug1: match: OpenSSH_6.0p1 Debian-3ubuntu1 pat OpenSSH* compat 0x04000000
debug1: Authenticating to 107.170.160.89:420 as 'adam'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr umac-64#openssh.com none
debug1: kex: client->server aes128-ctr umac-64#openssh.com none
debug1: sending SSH2_MSG_KEX_ECDH_INIT
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ssh-rsa SHA256:yaXBElIwQJJKsNcGAE8hlDPmD26DyzgZ9ruwtbhs6vo
debug1: Host '[XXX.XXX.XXX.XX]:420' is known and matches the RSA host key.
debug1: Found key in /Users/adam/.ssh/known_hosts:3
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: Roaming not allowed by server
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /Users/adam/.ssh/id_rsa
debug1: Authentications that can continue: publickey,password
debug1: Trying private key: /Users/adam/.ssh/id_dsa
debug1: Trying private key: /Users/adam/.ssh/id_ecdsa
debug1: Trying private key: /Users/adam/.ssh/id_ed25519
debug1: Next authentication method: password
deployer#XXX.XXX.XXX.XX's password:
debug1: Authentications that can continue: publickey,password
Permission denied, please try again.
when I run ssh -v deployer#XXX.XXX.XXX.XX -p 420
Thank you.

Answer 1

debug1: Roaming not allowed by server
To start with an aside, you should disable roaming or upgrade your ssh client.
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /Users/adam/.ssh/id_rsa
debug1: Authentications that can continue: publickey,password
debug1: Trying private key: /Users/adam/.ssh/id_dsa
debug1: Trying private key: /Users/adam/.ssh/id_ecdsa
debug1: Trying private key: /Users/adam/.ssh/id_ed25519
The above group of lines shows that your ssh client offered the key id_rsa to the server, but the server didn't accept it. The last three lines refer to default key filenames which ssh looks for, but didn't find in this case.
debug1: Next authentication method: password
deployer#XXX.XXX.XXX.XX's password:
debug1: Authentications that can continue: publickey,password
Then, your ssh client prompted you for a password and offered it to the server, but the server didn't accept it.
It's not possible to tell from the client trace why the server is suddenly refusing your key and password. There are probably at least half a dozen things that could cause this. To find out for sure, you'd have to get into the server and check the syslog logs for messages from sshd. These files are normally located in /var/log.
Offhand, here are some of the things that could be causing this:
The account which you're trying to log into has been locked by the administrator (or maybe the password expired).
The account which you're trying to log into doesn't exist; it's been removed, renamed, or you're misspelling it.
Someone with access to the account changed its password and altered the list of authorized keys.
IP addresses have changed, and you're not connecting to the computer which you think you are.
Hackers have gotten into the server and made any of a number of changes.