Very slow transfers, even on LAN – except for big files

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First: I have read FAQ — Syncthing documentation .

I’m running Syncthing 2.0.10 on my Arch machine, and I’m getting extremely slow upload speeds – from a few bytes/sec to around 30KiB/s. My two other targets are a local machine on the same network, and one at a major server provider, all running the same Syncthing version.

I have disabled relays everywhere. I have put in a local URL (tcp://192.168.1.2:22000), and it connects to it, but the speed is the same. It’s on WiFi, but when I try to scp a large file in the same direction, I get the expected high speed.

Having completely run out of ideas, I rebooted the Arch machine. After that, I got the expected speed, up to 8MiB/sec. But after a few minutes, it slowed down to the same slow speeds.

I try to restart Syncthing on all machines, but it has no effect on speed.

I am not sure exactly when this started, because I haven’t kept an eye on Syncthing for a while.

I’m not seeing any errors in the logs, it just logs file transfers as normal.

I set up a test folder with one large file, and shared it with the other local machine, and it blasted through at high speed. The other files that move slowly are mixed size, on average quite small, and a lot of them.

Is that it? Small files just move very slowly now? It really didn’t use to be like that. Perhaps a change in Syncthing 2? However, there’s not much CPU load to speak of, on the sender or receiver.

Any hints appreciated!

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Many small files have always been slower than large files, because there is a transaction cost to handling a file.

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Now I feel like I posted prematurely. I’m not sure I’ve interpreted everything correctly. Right now I’m transferring a ton of photos very quickly, but the speeds reported in the Synthing web app are still in the slow range.

I don’t want to waste anyone’s time – I need to do more research to clarify if there’s even actually a problem!

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