Bittorrent Sync Is Super Slow


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Have set up sync on my home and work PC's and loaded up a 25.2 GB of files, some big, some small, on the work pc to sync back to home. 


Seeing transfer rates of 60kB/s max, so it's been chugging away there for a couple of days


When I have the same folder in Dropbox, the upload from the work PC happened much quicker and when I download torrents at home using utorrent, I get up to 5 MB/s down.  Nice fast connections.


Is there some configuration thing that I'm missing? 

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Out of interest, what speed do you get uploading from work computer to Dropbox?


If your work computer hasn't finished indexing the folder, this would explain the slow speed.


It might be a misconfigured firewall/router problem on either end. Check to see whether the listening port (random port, listed in Bittorrent Sync preferences) is open. To open this port, try enabling "UPnP port mapping" on both ends (though it should already be enabled), if the network/router supports UPnP this will do the job; otherwise, you'll need to open the ports using the router interface (just UDP, not TCP). You might need to ask your work sysadmin to open these ports for you. Also, make sure software firewalls on your work & home computers aren't interfering with Bittorrent Sync (you might have to whitelist the activity of this application if the firewall allows you to do so, for example).


If these don't solve it, check CPU usage of running processes. You might spot an antivirus trying to scan everything being downloaded to home computer, or a struggling filesystem process. What are the OSes on your work and home computers?

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Just to report back:  Enabled uPNP on my home router and get similar-to-DB upload speeds from my work PC. 


Thanks for the help. 


Obviously something that affects speed greatly.  Maybe put something that could be highlighted during the startup/install procedure?  Check the port and suggest procedures for adjusting? 


Not sure I'll keep it that way.  Doing a bit of reading and having UPnP set on my home router seems to make it vulnerable to attack in some way. 


Thanks again. 

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Guest proactiveservices

It sounds like the computers could not create a direct connection to each other. This will be because of firewalls and/or NAT on both networks. In this case, BT Sync uses a relay to transfer the data. As the transfer goes via another system it slows matters down. UPnP overcomes the problems inherit in NAT and will automagically configure incoming firewall rules for the transfer. If you can set up the firewall and/or NAT port forwards on at least one network, it shouldn't need relay or UPnP.

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  • 2 weeks later...

If the computers are directly connected I believe the "Devices" tab show an icon with two arrows.

If the computers are connected via a relay server I believe the "Devices" tab show an icon with a cloud.


If this is true, then

What is your icon on the slow connection?


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