The client offers the possibility to synchronize using the local area network (LAN), internet or a custom server. The networking mode controls the (re-) connection behavior for the client. Traffic can be restricted to:

Server, LAN, Internet
Server, LAN
Server only

Overview:

Changing connection modes

Connection mode is set to LAN and Internet by default. To change it:

Enable the Advanced Mode.
Click on Preferences in the main window.
Click on Network.
Select a networking mode from the Connections drop down.

LAN networking mode

In LAN networking mode the client allows connections to IPs and IP ranges that are

on a the same subnet,
found by a network broadcast or
configured in the LAN IP List

only. Connections from IPs other than those above will be rejected in the LAN networking mode. On larger intranets it is often required to configure the LAN IPs list, because computers are not a part of the same subnet or broadcast domain. The LAN mode is also recommended when all network connections are established either locally or via VPN. This gives additional security, since no public internet connection are made at all. The more unrestricted LAN and Internet networking mode does not require this setup, but allows connections to foreign computers.

Server only networking mode

In Server only networking mode the client allows only connections to the server set under Preferences -> Advanced.

This actually disables any peer-to-peer traffic and keeps the connection to the server only.

LAN and Internet networking mode

In LAN and Internet networking mode the client tries to connect to

devices, which are members of own folders
found by a network broadcast
foreign servers to obtain new IP information about devices, which are members of own folders

There is no restriction of IPs or IP-Ranges like in the LAN networking mode.

Modifying the LAN IP list

To define, edit or remove IPs and IP ranges considered to be on the local area network:

Enable the Advanced Mode.
Click on Preferences in the main window.
Click on Network.
Use the add , edit or delete buttons to make changes to the list.