Hi I have just set up a WR11 with a single SIM and I have noticed that the 'Service LED' is not working as described in the manual.
Link to LED info
Instead of blinking to reflect the network mode it is just lit solid amber. The other two LED's work as documented. The unit is fully operational in all other respects and successful connects to the mobile network and passes traffic etc.
The device is running
FW Version: 5.2.11.4 (Jun 5 2015 04:36:56)