I’ve used SyncThing for about six years now, but I’ve never encountered this problem before this year.
Twice this year, my upload/download speeds have dropped to absolutely abysmal levels for extended periods of time. It says that it’s syncing, but the download/upload speeds stay a 0B/s for most of the time and go up to a maximum of 3KiB/s (for a few seconds) every 30 seconds or so.
Last time this happened, I put up with it for several weeks before someone suggested that I redo my folders. (new directory, new sync profile, etc) Luckily, that worked, but I don’t want to redo my folders because it’s a pain in the butt. [EDIT: One important discovery from last time is that simply deleting the SyncThing-specific directories (like .ts) and sync profile and renaming the synced directory DID NOT work]
All of my other internet things are fine.
I’m syncing between a laptop with Fedora 41 and an Android phone. Both devices are connected to a VPN full-time. The laptop is plugged in with an ethernet cord and the phone is over wifi. It’s been several days of this now. I’ve restarted both the phone and SyncThing on Android several times.
Last time I only noticed this happening to one folder, but this time it’s two.
How many files are in each of the affected Syncthing folders?
Typical size of file being synced?
Screenshots of Syncthing’s web UI with the folder and device panels expanded showing the details would be very helpful (feel free to redact details, but the more that’s visible the easier it is to debug).
Also, is it actually synchronising or is it just stuck? For example, if you put an empty file in the folder and wait, does it get transferred eventually?
I created an empty file called “THIS IS A TEST” (right click > Create new… > Empty file") on my laptop several minutes ago and there is now a .tmp file with that title on my phone.
EDIT: Seven minutes later, it is still a temporary file.
The screenshots all look normal with nothing that immediately jumps out as being a potential problem.
Have you reviewed Syncthing’s runtime log (web UI → Actions → Logs) for potential clues?
But given that it only started happening this year, and isn’t consistently slow, I’m inclined to think it might be the VPN. Was the VPN a new addition this year? Or has it been in place for the 6 years you’ve been using Syncthing? Have you run any diagnostics on the VPN?
I happen to also be using Fedora 41 with a 2023 Moto G series phone and Syncthing averages 47 Mbps upload speeds from Fedora (CAT5e UTP) to Android (802.11n) on a LAN. Although I’m not tunneling Syncthing thru a VPN, if I did with my WireGuard connection, I’d expect to see at least 40 Mbps since I’ve tested the raw throughput before.
I’m seeing an awful lot of these in the logs: syncing: no connected device has the required version of this file
I’ve been using the VPN for four years. The only difference is that I’ve been using Fedora since April. (I left Windows to avoid MS’s creepy new ““features””)
