# Slow sync speeds, although devices are in the same network
**URL:** https://forum.syncthing.net/t/slow-sync-speeds-although-devices-are-in-the-same-network/27269
**Category:** Support
**Created:** [October 29, 2026, 4:13am UTC](https://forum.syncthing.net/t/slow-sync-speeds-although-devices-are-in-the-same-network/27269 "2026-10-29T04:13:36Z")
**Posts on this page:** 12
**Page:** 1
### Author:  [@feklee](https://forum.syncthing.net/u/feklee)
#### Post date: [October 29, 2026, 4:13am UTC](https://forum.syncthing.net/t/slow-sync-speeds-although-devices-are-in-the-same-network/27269/1 "2026-10-29T04:13:36Z")
Setup:
- Router: Sony Xperia 10Ⅶ Android phone, also providing Internet connection by 5G
- Sender: PC with WSL / Win11pro running Syncthing v2.1.7, Linux (64-bit Intel/AMD)
- Receiver: Steam Frame with SteamOS running Syncthing v2.1.7, Linux (64-bit ARM)
When I try to sync a file from the PC to the Steam Frame, it can be very slow. _What might be the reason?_
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### Author:  [@tomasz86](https://forum.syncthing.net/u/tomasz86)
#### Post date: [October 29, 2026, 7:37am UTC](https://forum.syncthing.net/t/slow-sync-speeds-although-devices-are-in-the-same-network/27269/2 "2026-10-29T07:37:35Z")
We need more information, e.g. are the devices connected directly or via a relay? You can check this in the GUI when looking under Remote Devices. Also, are you testing with a single large file, or a large number of small files? Syncing the latter will always be much slower.
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### Author:  [@feklee](https://forum.syncthing.net/u/feklee)
#### Post date: [October 30, 2026, 3:16am UTC](https://forum.syncthing.net/t/slow-sync-speeds-although-devices-are-in-the-same-network/27269/3 "2026-10-30T03:16:34Z")
It says: TCP WAN
(although both devices are connected to the same WLAN, provided by my Android phone)
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### Author:  [@mraneri](https://forum.syncthing.net/u/mraneri)
#### Post date: [October 30, 2026, 5:33am UTC](https://forum.syncthing.net/t/slow-sync-speeds-although-devices-are-in-the-same-network/27269/4 "2026-10-30T05:33:59Z")
> [@feklee](#):
>
> both devices are connected to the same WLAN, provided by my Android phone
Do you know for sure that these devices can communicate with each other via LAN? Is your Android hotspot isolating wireless clients?
Can you ping one machine from the other via the local network IP address?
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### Author:  [@feklee](https://forum.syncthing.net/u/feklee)
#### Post date: [October 30, 2026, 7:01am UTC](https://forum.syncthing.net/t/slow-sync-speeds-although-devices-are-in-the-same-network/27269/5 "2026-10-30T07:01:26Z")
On the PC, I actually have two Syncthing clients running:
- `felix-x1t3-11` (Windows 11 Pro): If I connect this one to `frame`, the Steam Frame, then the connection type is _TCP LAN._ But this is not the one I tested.
- `wsl-linux` (Arch Linux VM running in WSL under Windows 11 Pro): This is the one I did the tests with. From the VM, I can ping `frame` or SSH into it. But in the other direction I obviously can’t, because the VM accesses the Internet through NAT.
I conclude, NAT is the problem.
_Is there any way to make Syncthing connect `wsl-linux` and `frame` by LAN?_
Otherwise, I think I’ll just sync from Windows directly. My rationale of using the Linux VM for this sync was that both sides use Linux. And it is nice to not run into issues with permissions or case sensitivity. But I think for the files I generally use, this is not really relevant.
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### Author:  [@fungs](https://forum.syncthing.net/u/fungs)
#### Post date: [October 30, 2026, 10:53am UTC](https://forum.syncthing.net/t/slow-sync-speeds-although-devices-are-in-the-same-network/27269/6 "2026-10-30T10:53:20Z")
AFAIK one-way direction is fine, if the shielded device dials the direct connection. Did you try adding the peers explicity via they internal dns name or IP? so on the device behind the virtual NAT (wsl-linux) add frame using its explicit tcp address (I don’t have the current syntax, look at the docs). You may also want to disable relay discovery for testing.
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### Author:  [@feklee](https://forum.syncthing.net/u/feklee)
#### Post date: [October 30, 2026, 1:20pm UTC](https://forum.syncthing.net/t/slow-sync-speeds-although-devices-are-in-the-same-network/27269/7 "2026-10-30T13:20:17Z")
If there is interest for debugging purposes, I can try setting the IP. But eventually that is not a stable solution. I use the devices with different hotspots. Local IPs are always changing.
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### Author:  [@mraneri](https://forum.syncthing.net/u/mraneri)
#### Post date: [October 30, 2026, 1:50pm UTC](https://forum.syncthing.net/t/slow-sync-speeds-although-devices-are-in-the-same-network/27269/8 "2026-10-30T13:50:06Z")
> [@feklee](#):
>
> If there is interest for debugging purposes, I can try setting the IP
The interest has to be yours. If you want to try to understand the cause then you can try it and see what’s the result.
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### Author:  [@bt90](https://forum.syncthing.net/u/bt90)
#### Post date: [October 31, 2026, 12:51pm UTC](https://forum.syncthing.net/t/slow-sync-speeds-although-devices-are-in-the-same-network/27269/9 "2026-10-31T12:51:50Z")
Our LAN detection is rather simple. If the IP of the remote device isn’t part of the subnets the local device is directly connected to, it’s considered WAN. The fact that your remote device is listed with a private range IP address is a good sign that the whole network path stays within your LAN.
tl;dr: the speed is most likely limited by disk or the internal Syncthing database
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### Author:  [@UsernamePassword](https://forum.syncthing.net/u/UsernamePassword)
#### Post date: [October 31, 2026, 1:31pm UTC](https://forum.syncthing.net/t/slow-sync-speeds-although-devices-are-in-the-same-network/27269/10 "2026-10-31T13:31:32Z")
Hello,
I also have very slow transfert speed in local network, from main PC to Nas Goal is to sync my /home/user folder, with some ignore, it takes 570Gb.
At 20 KiB/s, it will take forever.
I have tried to redo the all config, in case I missed something.. but still the same.. Speed is between 1 to 100 KiB/s
What is the strategy when we hav e to sync big folder ? is performing an initial rsync recommended ? So syncthing “just” has to maintain it ?
Or maybe I should use an another solution for syncing / backup my home folder.
Thank you for your advices. BR
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### Author:  [@tomasz86](https://forum.syncthing.net/u/tomasz86)
#### Post date: [October 31, 2026, 1:45pm UTC](https://forum.syncthing.net/t/slow-sync-speeds-although-devices-are-in-the-same-network/27269/11 "2026-10-31T13:45:16Z")
Syncing a large number of small files is going to be slow. If want to “speed up” the initial sync, please check [https://docs.syncthing.net/users/faq.html#can-i-help-initial-sync-by-copying-files-manually](https://docs.syncthing.net/users/faq.html#can-i-help-initial-sync-by-copying-files-manually).
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### Author:  [@UsernamePassword](https://forum.syncthing.net/u/UsernamePassword)
#### Post date: [October 31, 2026, 2:07pm UTC](https://forum.syncthing.net/t/slow-sync-speeds-although-devices-are-in-the-same-network/27269/12 "2026-10-31T14:07:04Z")
Thanks for your reply!
My desktop and my NAS are connected to the same local network, with a 1 Gbps connection. Not sur that qualify as a "not so fast network. Anyway, I will try what is recommended.
Thank you !