Wish if there was an option for Source/Destination address fields in the “Custom Policy Rule” (Outbound Policy) to be defined by DNS hostname (in addition to IP address). In this way, the peplink should periodically resolve the DNS hostname (good to have an option to configure this “Resolve Period”) to its set of IP addresses (it can be one or more IP addresses mapped to that single hostname), then apply that rule to this set of IP addresses.
I think you may find this in the new upcoming firmware 