Unfortunately, this is not possible on the RUT500.
RUT500 is an EoL product as of 2017-07-14 and is no longer supported. This may cause some security and compatibility issues with newer hardware. More information on our EoL policy and products can be found here.
If you enjoy Teltonika products, all of our devices running the latest RutOS firmware support the default route option in IPsec, which enables all of the traffic to be sent through the IPsec tunnel.