Is only internal syncing possible?


I’m very new to this so excuse ans stupied question…

  1. Should I see other devices with Syncthing installed in my local network and connet to them without typing theirs IDs manually into the other one? I needed to use their IDs to connect… Maybe that’s a problem already?

  2. I wanted Syncthing only to sync while I’m in my home network so I unchecked “Relaying”, “Global Discovery” and “NAT traversal” as I do understand “NAT traversal” as an in/out IP translation thing…

After unchecking all, it took a while and my Desktop lost connection to my both wireless devices…

Checking “NAT traversal” again was helping but after that I could realise traffic going out again… So what’s been send out for “NAT traversal”?

Cheers Markus

You can use Syncthing 100% locally with no problems, but please be specific about the environment and the devices (e.g. operating systems, non-standard hardware, etc.), because you may need to use custom settings in some cases (e.g. on Android you can’t use local discovery, and without global discovery enabled you will simply need to hard-code the IPs/hostnames instead).

Of course, locally or not, you still need to use the IDs and set everything up the same way. Please read up and if you haven’t already.

Thanks for your reply.

I use a Notebook with Windows 10 on LAN a Samsung Galaxy phone on WLAN and a Samsung Galaxy Tab on WLAN.

The router is an AVM Fritz!Box and it has two AVM WLAN Repeater.

All IP are set not to change in the Router.

As I sad, When I have “Relaying”, “Global Discovery” and “NAT traversal” on it works, without them not. So “Local Discovery” alone isn’t working because of the both Android devices? Two Windows devices or Linux would work with only “Local Discovery”?


Yeah, local discovery should be enough for Windows and Linux devices, but you also need to make sure that your firewalls allow direct connections. Specifically on Windows, you need to both set your network profile to “private” (instead of “public”), and the Syncthing executable itself needs to be allowed to connect on private networks as well (which is normally done through a Windows Defender pop-up on the first run).

If you don’t want to use global discovery, then you may need to hard-code the addresses, e.g. on the Android side for the Windows device change the default dynamic to dynamic, tcp:// or dynamic, tcp://windowscomputername, and so on.

That’s what is was, I tried another Windows PC and it runs fine, they detect eachother on the netweork, it’s really about Android…

So I changed the addresses of the Android devices from dynamic to static IPs like TCP://192.168.20 and .21 and the Android device went “up to date” again.

THANK YOU VERY MUCH!!! :slight_smile:

Didn’t hear/read about this Android problem…

PS: Can I only use or do I have to use tcp:// as well?

One more question.

When I want my Notebook which shares folder with each, my smartphone and my Tab, to be the intorducer to my 2nd Windows PC which I added just for testing eralier that day…

What do I have to do?

I went into Syncthing on my Notebook “advanced > devices > notebook” and ticked introducer.

I went into Syncthing on my 2nd Windows PC “Remote Devices > Notebook > Edit > Sharing” and ticked Itroducer.

Is that correct?

Because the 2nd Windows PC doesn’t get the infos about the smartphone and tab…

With just a few devices, you really don’t need to use the introducer feature (as its main use case is with larger setups, e.g. 10+ devices or similar), but if you want to use it, you should only set a single device as such.

In other words, if Notebook is intended to become an introducer, you should mark it as such on your other devices. You don’t need to do anything on Notebook itself.

Also, just in case you haven’t seen it already, please check

The standard scheme is tcp://, so I’d say yes. I’d keep dynamic there as well, as you never know whether some workaround is found and local discovery starts working on Android in the future again.

I read through that link already and I do understand, I did the steps mentioned above but the 2nd WIn PC doesn’t receive the information about the Android devices from the Notebook…

The Android device see eachother now, that worked out well…

So the 2nd Windows PC isn’t seen by the Android devices and the 2nd PC doesn’t see the Android Devices…

Anyway, I stoped that now because after seeing eachother both Android devices said “synching” without having a shared folder… That was trange so I stopped it…

Thanks for all your help and patients

Alls the best to you


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