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While similar to the Routing menu, the MultiWAN Routing menu allows you to affect traffic outbound in case of multiwan scenario. In this page you can define advanced parameters to make a connection “sticky” to a specific WAN. Directing traffic outbound will implicitly affect the corresponding return traffic as well, so a packet going to WAN0 is expected to return only to the same interface.

On: If enabled makes the rule active.

Protocol: All/TCP+UDP/TCP/UDP/ICMP -

Here you can define the transport protocol that should be matched by the rule. Please not there are hundreds of layer 4 protocols this page and this setting in particular refers to the most common only.
Source Address:

All/IP

MAC

Filters in the defined source of traffic. All stands for all LAN devices, IP allows you to define a specific IP or set of IPs in a netmask syntax (e.g. 192.168.1.0/24), where MAC binds the rule to a defined MAC address only.

Destination Address:

All

IP

Domain

Similar to the source IP, the destination address makes the rule more restrictive based on/or destination address. This can be defined as ALL (as in Internet), IP address or set of addresses, defined in a netmask format or even a destination domain.

Selected WAN: WANx - Specfies the logical interface where the defined traffic should be sent outbound.

Description: In this free text field, you can enter notes to make management easier.

Please note that the rules defined will take precedence over any WAN's weight-related setting.