Sublime SFTP connection failure

I am trying to connect a remote server that requires SSH key to connect. I am using Sublime Text 3's SFTP package for development purposes. I can connect through SSH, but sublime sftp fails. I have used standard configuration for this but the Connection timeout error is being shown when I sync both, local and remote. I have included relevant details following.

sftp-config.json

{
    // ... all other settings untouched ...
    "type": "sftp",
    "host": "<ipaddr>",
    "user": "ubuntu",
    "remote_path": "/home/ubuntu/devproject",
    "connect_timeout": 500,
    "ssh_key_file": "C:/Users/Dev-Laptop-008/Documents/MobaXterm/home/.keys/devkey.pem"
    // ... all other settings untouched ...
}

Sublime console error

Connecting to SFTP server "ipaddr" as "ubuntu" ..... failure (Connection timeout)

Remote server's auth.log

Jun 30 05:45:00 developers-den sshd[6475]: Connection closed by authenticating user ubuntu <ipaddr> port 63382 [preauth]

Solution 1:

Resolved the issue by turning on the sftp logs (go to Preferences: SFTP Settings in Sublime). My logs included Unable to load key file "<filename>.ppk" (PuTTY key format too new). Found that issue answered in this StackExchange question.

Summarizing, create a new .ppk file based on an existing .pem file using PuTTYgen after changing the following setting:

Key -> Parameters for saving key files... -> PPK file version: 2

Final sftp config:

{
    "type": "sftp",
    "host": "<ip address>",
    "user": "<username>",
    "remote_path": "<server path>",
    "connect_timeout": 30,
    "ssh_key_file": "<filename for ppk file>.ppk"
}