Help Center


Peers aren't connecting


If peers in a different network (not in your LAN) try to connect, but do not show up on Peer List window, there may be a few things happening that are preventing the peers from connecting. 

  • Firewall is blocking tracker and relay (system’s or router’s firewall). 
  • Listening port may also be blocked. Go to Advanced preferences and change the listening port to some value between 1024 to 65535, excluding 3000. Or forward the port in your router. 
  • Unable to reach config.usyncapp.com/sync.conf. Check with wget.
  • Your PC may have been migrated using a migration tool, and likely has the same peer ID as it did previously. Completely reinstall BitTorrent Sync on one device.
  • Bonjour service was not launched on Mac.


Please Note: T-Mobile in US is currently blocking Sync traffic on their mobile network. Check to make sure you are on WiFi if this is your mobile operator. 

If peers are in the same network and you are trying to connect devices over your LAN, these may be causing the problem:

  • Multicast packets are not allowed
    Make sure that your firewall is not blocking UDP packets coming to port 3838.
  • Direct multicast is disabled in router settings
    Check your router settings. Some of routers have features that allow to map multicast to unicast or simply block multicast packets. These settings might be absent at all or might look different depending on router model.
  • A computer may have multiple Network Identification Cards (NICs). Switching to the second network card may help resolve this.

Still having problems with connection? Please collect debug logs from two peers that cannot connect and send them to support! 

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