The physical link is not established reliably in a random manner when the TK1 SOM is powered on with the Linux LXDE Image running on it. The physical link led of the switch the SOM is connected to is not lighting up (indication for the proper establishment of a physical link). The behaviour occurs randomly.
I wrote a test script which pings the SOM every minute and switches a power supply via a Phidget DigitalOutput off and on whenever the board is pingable. If the board is not pingable the script is halted in endless loop and the SOM is kept powered on to enable its investigation over the serial interface.
This issue relates to a similar issue in u-boot.