This feature is so brand new that it seems not to be documented in detail yet. But I found a recipe in the Cookbook (pg. 16 ff).
There is an updated article in the " What' s New in 5.2.1" .
You can set this up using ' weights' which effectively control the percentage of traffic using one or the other link. Say, with weights of 99 and 1 you should see 99% of the traffic using wan1 and only 1% using wan2.
If you want spillover instead then specify spillover. Depending on the limits set one link will be used first and the other only if bandwidth is exceeding the spillover threshold.
Failover will occur if link health monitoring is set up just like DGD used to work.
Ede Kernel panic: Aiee, killing interrupt handler!