I've been trying to log CAN data using CAN2 in listen mode and connected to a different bus in the car ,I stopped the logging to the SD card yesterday and was going to test network streaming the data directly today, since I was having problems downloading the file, but I noticed that it goes to "Off" after an unspecified time. 

Yesterday I made sure it was on "Listen", after failing with the SD card file. And there is no mention of a timer, in the dev docs.

Oscar