Want to sync data (music) to sdcard on Android 7.0 I'm looking for something that would allow me to keep a folder (music files) in sync between a main folder on a PC and a folder on an external SDcard in a (not rooted) Android 7 phone.  Would prefer wireless, but at this stage would be happy with USB connection as well.

My attempts so far:


Run SSHDroid on android and rsync from PC. 


SSHDroid lets me see everything, but any time I try to write to the external SD card, I get permission denied.  I can write to internal memory only.


Run network server from ES Explorer.


Same problem to SSHDroid.  Can't seem to write to the external SD card.


Mount phone on windows via USB and use PC sync tool.


While I can see the folders in Explorer (and can copy files to them), I can't seem to access them from any other windows app.  When I do "Save As..." in an application, I can't see the phone in the list of devices that I can save to.  So I can't seem to point any of the windows sync tools to it.  With Cygwin-based rsync, I don't have a drive letter to access.


MyPhoneExplorer.


This is a client/server app for the PC and the phone.  It's easy to configure access to the SD card and can sync data back and forth.  So this seems perfect, except the file sync portion doesn't like large folders. Small syncs succeed, but when I ask it to sync my music folder (over 15GB and 9000 files), the program crashes while trying to analyze stuff before the transfer starts.

Any other solutions I should be trying (or anything I might be doing wrong with the previous attempts)?

Actual phone is LG K20 V
If you really want to keep the entire directory (and possibly its sub-directories) in sync, so that their content is "mirrored", FolderSync would be a good candidate. It's an app running on your Android device that can communicate with a plethora of protocols:

  
FolderSync Screenshots (click images for larger variants)

As you can see in the first screenshot, it not only supports many clouds and FTP, but also Samba/CIFS (Windows PC, second from bottom). SSH can be used as well (that's how I use it with my Linux machines). FolderSync also allows you to schedule syncs, even limit that to when you're connected to your home WiFi. The paid version also has tasker support.

I'm not affiliated with the product or company, but I'm using the paid version happily for years on multiple devices :)