LAN-Sync is an advanced option found in Preferences - Network. With it enabled, when one of your computers starts a download (either to synchronize a file or for a normal download), it first asks nearby computers on your local network if they have that file. If one of them does, then the local copy is downloaded in order to obtain it faster.
That sounds like a good thing and it is. There is however a downside, which is that it is suspected to be associated with a number of problems. For that reason SpiderOak ONE comes it it disabled by default, and we normally suggest that that it not be enabled. The following is provided for your information, but if you ever have subsequent problems with SpiderOak ONE then your first troubleshooting step should be to deactivate LAN-Sync.
It's important to know that LAN-Sync does not make your computers sync without our servers. We only sync or download files that are already on our remote servers. The application decides first what it wants to download, querying the information stored on our servers, and then it starts the download, possibly downloading from a local source.
Many users find that they have to manually configure their firewalls and other security software before LAN-Sync will work for them. That is because some malware spreads itself across local networks in similar ways, so security software rightly blocks such behavior by default. That is a good thing, but it does mean that LAN-Sync often needs adjustments to be made on your end before it will work. Be sure that your firewall or other security software is set to allow SpiderOak ONE to:
- Open a UDP listen port on 21327 or 21328
- Send UDP broadcasts to these ports
- Open a TCP listen port on a random address
- Open a TCP connection to the other client