Thanks, I have internet connection according the simcard managementportal and the connected enddevice is working as well (without the power to ssh or reboot the 4g-router).
I'v tried the SMS text message with our password and default password but no reply on the SMS text message.
Strange, I will replace the rut240 unit next time I'm nearby the client, maybe something went wrong while configuring the device as the internet to the clients end device is working it has low prio.
thanks for your help so far!