You can access your SFTP server on Android in quite an easy manner using B1 File Manager 0.6. It can be done in just a few easy steps.
Step 1: Preparations
You'll need a fresh version of B1 File Manager for Android. It's available for free on Google Play.
Step 2: Start Establishing Connection
Call the sidebar by tapping B1 icon or swipe from left side of the screen and tap the plus icon in the Networks. This will take you to the New connection window.
Step 3: Type in Server Data
OK, you need to input some data in order to connect.
1. Server address.
4. Display name (optional)
5. Port (22 by default)
6. Remote path (optional)
Tap Connect once ready.
Step 4: Transfer and Manage Files
By using the Upload button in the top-right corner you can upload any files or folder from your device to server.
In order to download files from server simply tap them.
You can multi select files and folder in order to upload/download more then one at a time.
Your connection will be saved and available from the Networks menu.