I have the same problem. I have used 2 different SIMs (one vodafone, one giff gaff - using o2 network), both 4g, both work in my phone, and my housemate's. Neither work in the router. They both show that they're registered on the network, and are seeing a 4g signal, but both times the data connection status is Disconnected. Pretty sure I have got all the settings correct...they're all listed on the forums of the service providers, I have also used different combinations of settings to no avail. As a side, I have not been able to get the router to work on a wired connection either - I have tried plugging it into internet socket on the wall, and also into my existing router and setting it to passthrough. In the latter situation, neither the RUT955 or my existing router see each other. The only function I have working the the wifi.