Syncthing -- Building a Private OneDrive, Centered on NAS via Docker Desktop
If you want a self-hosted, cross-platform synchronization solution like OneDrive, Syncthing is a powerful tool. This guide walks through how I used Docker Desktop and a NAS as the central hub to keep documents synchronized across Windows, macOS, and other devices.
📦 What is Syncthing?
Syncthing is an open-source, continuous file synchronization program. It synchronizes files between two or more computers in real time, safely protected from prying eyes.
🧩 System Structure
- NAS (QNAP / ZimaBoard / etc.): Runs the core Syncthing instance in Docker.
- Windows PC & MacBook: Each runs Syncthing and syncs through the NAS.
- Private network or Internet: All communication is peer-to-peer via QUIC/TCP/relay.
🐳 Deploying Syncthing on NAS via Docker Desktop
On your NAS (or PC acting as central node), use Docker Desktop to run the container:
Docker Image
linuxserver/syncthing:latest
Ports Mapping
| Container Port | Host Port | Purpose |
|---|---|---|
| 21027/udp | 21027 | Local discovery broadcast |
| 22000/tcp | 22000 | Main sync traffic via TCP |
| 22000/udp | 22000 | Sync traffic via QUIC |
| 8384/tcp | 8384 | Web GUI |
You can map different ports if you like, but remember to forward or open them in your NAS/router firewall.
Volume Mounts
| Host Path | Container Path |
|---|---|
E:\Docker\syncthing\config | /config |
E:\daisuke | /data |
Ensure both paths are granted permission in Docker Desktop → Settings → Resources → File sharing.
🛠️ First Launch Issues
Common Errors & Fixes
1. permission denied errors
mkdir /run/s6-rc: permission denied
→ Make sure Docker Desktop has access to the folder (Windows: File sharing enabled + Admin privileges).
2. Folder path missing
Error on folder "Windows-Documents": folder path missing
→ Check the folder path in Syncthing settings. Ensure the actual path exists and is shared with Docker.
3. setting permissions: operation not permitted
→ This usually happens on Windows. Disable these in folder settings:
- "Send Ownership"
- "Sync Ownership"
- "Send Extended Attributes"
- "Sync Extended Attributes"
⚙️ Autostart Syncthing Container
To make the container auto-start on reboot, use Docker Compose or set the --restart unless-stopped option in docker run.
Docker Desktop GUI doesn’t offer this toggle directly.
If you're using CLI:
docker run -d \
--name=syncthing \
--restart unless-stopped \
-p 8384:8384 -p 22000:22000 -p 22000:22000/udp -p 21027:21027/udp \
-v E:/Docker/syncthing/config:/config \
-v E:/daisuke:/data \
linuxserver/syncthing:latest
🧩 Sharing Strategy (Recommended Setup)
- Let NAS share folders to Windows and Mac.
- On Syncthing GUI:
- NAS adds folders.
- Windows/Mac are just "receive & send" devices.
- Only NAS should be shared with both endpoints; avoid direct sync between Mac and Windows to reduce conflict.
✅ Tips for Better Stability
- Use NTFS or ext4 for mounted folders, avoid FAT/exFAT.
- Disable permission syncing on non-Linux hosts.
- Use fixed folder paths and avoid renaming folders after setup.
- Always check for
.stfolderinside shared folders (used by Syncthing to mark valid sync).
🎉 Result
Now I have a fully private, real-time, cross-device syncing system that works just like OneDrive — but it’s 100% under my control.
Happy syncing!
::: tip
If you file always automatically gain a .temp suffix, or there's a ```
Error renaming "... .ipynb.tmp" to "... .ipynb" while normalizing UTF8 encoding: file does not exist. You will want to rename this file back manually.
warning on your control panel, please refer to [this blog](logs/errorSolutions/fix-syncthing-autonormalize.md)
:::
> Written by daisuke — powered by NAS + Docker + Syncthing 🚀