Interface and DNS Configuration¶
The first two items to configure for Multi-WAN are interfaces and DNS.
Setup the primary WAN as previously described in Setup Wizard. Then for the additional WAN interfaces, perform the following tasks:
Assign the interfaces if they do not yet exist
Visit the Interfaces menu entry for each additional WAN (e.g. Interfaces > OPT1)
Enable the interface
Enter a suitable name, such as
Select the desired type of IP address configuration depending on the Internet connection type.
Enter the remaining details for the type of WAN. For example, on static IP connections, fill in the IP address, subnet mask, and add or select a gateway.
DNS is critical for Internet connectivity. For multi-WAN to function correctly the firewall must always be able to resolve DNS for itself and on behalf of local clients utilizing the DNS Resolver or DNS Forwarder.
If the firewall configuration only includes DNS servers from a single WAN then an outage of that WAN results in a complete Internet outage since DNS will no longer function.
If the DNS Resolver is in resolver mode, see DNS Resolver and Multi-WAN.
If the DNS Resolver is set for forwarding mode or if the DNS Forwarder is in use, then the firewall must be configured with DNS servers for each WAN as described in DNS Forwarding and Static Routes.
DNS Resolver and Multi-WAN¶
The DNS Resolver can work with multi-WAN but the exact configuration depends on the desired behavior and current settings, especially the chosen DNS Resolver mode.
If the DNS Resolver is using its default resolver mode, such as for environments which require DNSSEC, then it can still function with multi-WAN but requires using failover for the default gateway. See Managing the Default Gateway.
Even in resolver mode if the firewall is set to use or fall back to remote DNS servers under System > General, DNS Resolution Behavior, then it is still useful to configure gateways for individual DNS servers as described in DNS Forwarding and Static Routes
DNS Forwarding and Static Routes¶
When using the DNS Resolver in forwarding mode or the DNS Forwarder, the firewall uses its routing table to reach the configured DNS servers. This means without any static routes configured, it will only use the WAN with the default gateway to reach DNS servers.
Gateways must be selected for each DNS server defined on the firewall. This forces the firewall to use a specific WAN interface to reach a given DNS server. At least one gateway from each WAN should be selected where possible.
Most ISPs prohibit recursive queries from hosts outside their network, hence the firewall must use the correct WAN interface when accessing DNS servers for a specific ISP.
DNS servers obtained from a dynamic WAN are automatically routed back out the appropriate dynamic WAN.
To configure DNS server gateways:
Navigate to System > General Setup
Define at least one unique DNS server for each WAN
Select an appropriate gateway for each DNS server so it uses a specific WAN
If the gateway entries for these WANs use DNS servers for their monitor IP addresses, ensure there is no conflict between those values and the selected gateways in this list.
Each entry must be unique; the same DNS server cannot be entered more than once.
If using the DNS Resolver, ensure it is set for forwarding mode:
Navigate to Services > DNS Resolver
Check Enable Forwarding Mode
Uncheck Enable DNSSEC Support
Click Save, then Apply Changes