IGEL UMS sends the magic packets as UDP datagrams to port 9. In order to work for different subnets, this has to be supported by the routers involved.
Wake on LAN settings can be configured in UMS Console under UMS Administration > Global Configuration > Wake on LAN.
UMS supports sending Wake on LAN magic packets to
the broadcast address
the last known IP address of the device
all defined subnets
the network address of the last known device IP address (define one or more network masks to be applied)
a dedicated Wake on LAN proxy to wake up thin clients in another network; see How to Use a WoL Proxy for Waking up Devices in the IGEL Environment