Just to give an update on this topic. We got a little bit further. We have two devices of which one is sending data to the Sierra Wireless via UART. If the services that send the UART data are shut down and the WP76xx is rebootet, UART works flawlessly but if the services are running, something seems to happen with the Sierra’s UART but we haven’t figured out what yet. It might be some control character problem because sometimes we receive something like “^M” as character. I don’t know but it’s very strange. Is there a plan to update the Kernel any time soon? Because we are using completely new devices which still run on Kernel 3.18.140 which is heavily outdated and seems rather buggy to me.