Sync v2.5 introduced option to optimise speed of syncing across the internet - WAN optimisation. This option is available with Sync Business Accelerator license.
Sync uses new Micro Transport Protocol (uTP2) to intelligently transmit data across the network. This protocol can detect available bandwidth or network congestions and adjust its behavior accordingly in a smart way - increase data transit if possible, or avoid data loss and unwanted packet retransmission on a busy pipe.
To start using the optimised data transfer, apply the Business Accelerator license on one of the devices and share the rest of the seats with others. Enable option "WAN optimisation" in Sync settings on all peers where you need to option to work.
If running Sync in config mode, add parameter "net.enable_utp2": true to the config file and restart Sync.