Syncthing is very slow even on LANe

I have syncthings setup on 4 PC. Three windows 10 machines and a linux server,

Lets call them PC1 PC2 PC3 SR1

PC1 and SR1 are on the same LAN connected by gigabit ethernet, and yes it gets that speed. I can transfer large files to it extremely fast. Lets cause this LAN1

PC2 and PC3 are on the same LAN, They are also on gigabit ethernet but I have not tested the transfer speeds of files. Lets call this LAN2

Total amount of synced data is around 40GB

Network 1 and 2 are connected via the internet (obviously) Network 1 is connected via 600/50(Mbps) and Network 2 is connected by 80/20.

Syncing all the devices is painfully slow. I left if two days and it hasn’t finished yet. A lot of the time the speed seems to be sitting at 0.0kbps. Even syncing within LAN1 I havent seen it go over 30kbps and most of the time its a fraction of that.

I tried removing PC2 and 3 so it could just sync between LAN1 but its still painfully slow. Worth noting that most of the files are already on both devices. PC1 has a few files changed, and was added as a new device due to windows reinstall but it already has a local copy of all the files on SR1. SR1 got a little behind because I unplugged it to move it. Expected it to catch up fairly quickly but it sat there for days.

Logfile attached bigmond-syncthing-log.log (9.6 MB)

Have you checked the FAQ?

Ok lets address the FAQ page, should have added that to my post, sorry.

Are we connected by Relay, No we are connected on lan directly. I dont think any of the devices have said relay.

Are the devices low powered. No not really, all of them are reasonable. PC1 is a ryzen 5 machine, the others are all AM3.

I havent caught it using many resources either, for the moast part the PCs are idle. Some normal usage but its not like syncthings is using much resources or pushing the CPU or hard drives.

Please check the IP addresses that Syncthing lists under remote devices. If they’re not your local addresses, then they’re probably relays.

Also, because Windows is involved, please verify that your network connection in the Windows settings is set to “private” and not “public”, because otherwise Windows won’t allow direct connections, meaning that Syncthing will be forced to use relays.

Ok I’m looking from Lan 1 now, sitting at PC1

For lan 1 the syncthing ports are forwarded to SR1 SR1 lists its lan lap IP:22000 The other two list wanIP, one lists port 22000, the other lists port 18887

From SR1, PC1 lists lan IP:22000 PC2 lists wan IP:22000 PC3 lists wanIP :62475

The devices on Lan 2 show essentially the same thing, local device is down as lanIP, the other two are down as wanIP, one uses default port the other uses another port.

Network is set to private.

Can you try disabling relaying completely in the Syncthing settings and then see whether the devices can still connect, and if yes, what the transfer speed is then?