I have 2 internet lines hook up to the appliance as Primary and Secondary LAN. when I turn the Load Balancing On, the internet disconnected. I turn it off. it works.
anyone know what I may have done wrong?
I am new to this Safe@office 500. any instructions on how to properly add it?
thanks.

Per the documentation and my own expereince enabling ISP load balancing.

Configuring WAN Load Balancing

If your network is prone to congestion, for example in large offices which include multiple
active clients and/or servers, you can increase the amount of available bandwidth by
configuring WAN load balancing. By default, the UTM-1 appliance routes all traffic to the
primary Internet connection, and the secondary Internet connection is used only when the
primary connection is down, or when a routing rule specifically states that traffic should be
sent through the secondary connection. WAN load balancing automatically distributes
traffic between the primary and secondary connections, allowing you to use both
connections in parallel.
When one IP address sends packets to another IP address, the UTM-1 appliance examines
each Internet connection's recent bandwidth utilization in kilobits per second to determine
its load. The UTM-1 appliance then enters the source-destination pair in a load balancing
table and specifies the least-loaded Internet connection as the connection to use for traffic
between this pair. To prevent disruption of stateful protocols, the UTM-1 appliance will
route all traffic between this pair to the specified Internet connection, so long as the pair
remains in the load balancing table.


Note: By default, a source-destination pair is removed from the load balancing table
after 1 hour of inactivity. You can change the default value via the CLI. For
information, refer to the Embedded NGX CLI Guide.


Note: In order for WAN load balancing to be effective, there must be more than one
active source-destination pair.
By default, the load distribution between Internet connections is symmetric; however, you
can configure non-symmetric load balancing by assigning a different load balancing
weight to each Internet connection. For example, if you assign the primary connection a
weight of 100, and you assign the secondary connection a weight of 50, the UTM-1
appliance will only route traffic to the secondary connection if the primary connection's
current load is more than twice the secondary connection's current load. Therefore, to
ensure full utilization of both Internet connections, the ratio between the connections' load
balancing weights should reflect the ratio between the connections' bandwidths.


Note: To ensure continuous Internet connectivity, if one of the Internet connections
fails, all traffic will be routed to the other connection.