It is easy.Use newest firmware. I use a Nexus7 2012 running Lollipop factory unrooted.
ES file explorer has full access to the Sandisk connect wireless wifi USB drive.
Upload, download, multiple files, etc . No restrictions as in sandisk app. Only problem I have noticed are screwed photo thumpnails.
- connect to drive wifi
- open sandisk app / connect drive / goto settings
- copy web URL (e.g. 175.xx.xx.xx/wdf)
-Open ES file explorer newest release, goto Network / network - tap + for new server
- add new "webdav " server. Paste copied URL. Standard port 80
- thats it!
Enjoy!!!
