Hi,
the router RUT950 has an problem with data limit. Sometimes it starts sending SMS that it reach limit but it is not the right value of limit. Sometimes it send sMS every 500Mb or 50Mb or 3Mb....
The similary error based on data limit is when it reach the right limit. After it reach limit the router is switching between the SIM cards for some hours without reason. At the events log is no information why the switching starts and the restart of the router does not fix it.