Cannot login with SSH USERNAME@IPADDRESS, receive "Permission denied (publickey)" despite root user working

So the issue is that I can login to my server just fine using:

ssh root@SERVER_IP_ADRESS

But when I try to login with a user I created from root:

ssh USERNAME@SERVER_IP_ADRESS

I get:

Permission denied (publickey).

The steps I went through before this.

1. SSH generated a key
2. Created an Ubuntu 16.04 droplet with given SSH key.
3. SSH into server with root
4. $ adduser user_name
5. usermod -aG sudo user_name

At this point I switch into my newly created user and can see that it’s created and that the user has been added to sudo group with:

id -Gn

it displays “user_name sudo”

I’ve verified that the public key is in ~/.ssh/authorized_keys of both my root and user directory.

I’ll “exit exit” out of user and server. And attempt to ssh with user to no success.

Even attempting:

ssh -i PRIVATE_KEY USER_NAME@SERVER_IP_ADDRESS

results in the same “Permission denied (publickey).”

I tried to use the ssh -v command to see what may be different between root and user.

ssh -i PRIVATE_KEY USER_NAME@SERVER_IP_ADDRESS -v

OpenSSH_6.9p1, LibreSSL 2.1.8
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 21: Applying options for *
debug1: Connecting to 165.227.83.215 [165.227.83.215] port 22.
debug1: Connection established.
debug1: identity file test-key-fem type 1
debug1: key_load_public: No such file or directory
debug1: identity file test-key-fem-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_7.2p2 Ubuntu-4ubuntu2.4
debug1: match: OpenSSH_7.2p2 Ubuntu-4ubuntu2.4 pat OpenSSH* compat 0x04000000
debug1: Authenticating to 165.227.83.215:22 as 'kevin'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client chacha20-poly1305@openssh.com <implicit> none
debug1: kex: client->server chacha20-poly1305@openssh.com <implicit> none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:HSPEtljdgqP4d9ZmZKSYGW9iyBfhclnWAKrbnYQam9Y
debug1: Host '165.227.83.215' is known and matches the ECDSA host key.
debug1: Found key in /Users/klufkin/.ssh/known_hosts:9
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Offering RSA public key: test-key-fem
debug1: Authentications that can continue: publickey
debug1: No more authentication methods to try.
Permission denied (publickey).

ssh -i PRIVATE_KEY ROOT@SERVER_IP_ADDRESS -v

OpenSSH_6.9p1, LibreSSL 2.1.8
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 21: Applying options for *
debug1: Connecting to 165.227.83.215 [165.227.83.215] port 22.
debug1: Connection established.
debug1: identity file test-key-fem type 1
debug1: key_load_public: No such file or directory
debug1: identity file test-key-fem-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_7.2p2 Ubuntu-4ubuntu2.4
debug1: match: OpenSSH_7.2p2 Ubuntu-4ubuntu2.4 pat OpenSSH* compat 0x04000000
debug1: Authenticating to 165.227.83.215:22 as 'root'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client chacha20-poly1305@openssh.com <implicit> none
debug1: kex: client->server chacha20-poly1305@openssh.com <implicit> none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:HSPEtljdgqP4d9ZmZKSYGW9iyBfhclnWAKrbnYQam9Y
debug1: Host '165.227.83.215' is known and matches the ECDSA host key.
debug1: Found key in /Users/klufkin/.ssh/known_hosts:9
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Offering RSA public key: test-key-fem
debug1: Server accepts key: pkalg ssh-rsa blen 279
debug1: Authentication succeeded (publickey).
Authenticated to 165.227.83.215 ([165.227.83.215]:22).
debug1: channel 0: new [client-session]
debug1: Requesting no-more-sessions@openssh.com
debug1: Entering interactive session.
debug1: client_input_global_request: rtype hostkeys-00@openssh.com want_reply 0
debug1: Sending environment.
debug1: Sending env LANG = en_US.UTF-8
Welcome to Ubuntu 16.04.4 LTS (GNU/Linux 4.4.0-119-generic x86_64)

The main difference I see is that when I ssh with root user I’m getting this line:

debug1: Server accepts key: pkalg ssh-rsa blen 279

I’m running this all on my Mac OSX. And have no config file in my /.ssh directory on my computer.

Please let me know if there is something I am missing or if you need more information to help me. This is all fairly new to me so it’s not super clear as to how to triage this issue.