Slow sync from android to windows

Support Android
1

Hi.

I sync my phone camera folder (3400 files / 34GB) and have a very slow sync from android to windows.

Slow means that syncing takes forever. I have the impression it can do fast transfers (up to 100MBit/s), but there are really long gaps where nothing happens and transfer rates go down to 0.

I have read about the problems with the android storage interface, however I understand here the problem is mainly with receiving many small files and store them on the phone. My main use case is uploading from phone to PC. After vacation, uploading the ~1GB new photos takes hours.

What I tried:

  • Change to the new syncthing fork → same issue
  • sync to a Windows and a Linux client on my PC → no difference
  • sync between windows + Linux client → after hours of sync from phone → Windows, I start the linux client and the same amount syncs between minutes.

Further infos:

  • phone: Pixel 7a with android 15
  • path to the shared folder on android: /storage/emulated/0/DCIM
  • all clients are in the same LAN (connection type: TCP LAN)
  • GSAM battery monitor shows huge runtime on job/com.google.android.providers.media.module/com.android.providers.media.MediaService
  • While the camera sync is stalling, a different folder can upload 200MB in a few seconds.

Is this a known android problem?

2

Try the old version 1.9. It’s worked wonders for me:

3

Not really, the known problem is that syncing to Android will be slow if you’ve got thousands of files located in the same folder, however, the other way around, there should be no issues.

Can you post screenshots of the Syncthing Web GUI from both sides? Please make sure that the information under “Remote Devices” is visible. On Android, you can access the Web GUI from the left slide-out menu.

4

Here the screenshots from the PC and the phone.

Screenshot PC
Screenshot PC1160Ă—814 56 KB
screenshot-phone
screenshot-phone1080Ă—2400 179 KB

5

I was worried that your devices might be connected via a relay, which could cause the slow sync, however it doesn’t seem to be the case. Not sure whether it will have any effect on the issue at hand, but you seem to be still using the now deprecated official Syncthing for Android app, so I’d like to suggest switching to Syncthing Fork, which is kept being updated. You can transfer your current config to it (see https://github.com/Catfriend1/syncthing-android#switching-from-the-now-deprecated-official-version).

6

Seriously look at my 1.9 post and try it.

7

Came here just to say “me too” and hopefully include useful data. I was running Syncthing-Fork and was trying to sync photos from Android to a computer on my local network. Details:

  • Syncthing Fork version 1.28.1.1
  • Connection type is always “TCP LAN”, run mode is wifi only
  • Folder is /storage/emulated/0/DCIM
  • Contains 3278 photos/videos, 72 GB of data
  • Let it run for 24 hours and it still was only half done before I killed it
  • It would consistenly wait for long periods of time with 0 B/s upload speed, then have little bursts of 1 MB/s upload for a second, then stop

So I took the advice of alswkd4 and installed Syncthing 1.9 from the link he sent and it worked like you’d expect:

  • Remaining 40 GB or so synced in about 30 minutes
  • Maintains consistent 20-30 MB/s upload speed

So something definitely changed in later versions of syncthing for android that caused an extreme loss of performance for this use case.

Note that I’ve been using the recent version of Syncthing Fork to sync other things to/from Android (also under /storage/emulated/0) without problems. So it’s something about the quantity or size of the photos folder.

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