Exasperated beyond belief with this issue. Briefly, use MR600 in static caravan. Last week it dropped the internet connection then re-established it. Dropped off again then nothing. Brought it home and managed to connect whilst hardwired to BT modem. Soon as detached from modem, connection lost. Reset router, checked SIM card. Updated firmware but is a hit of a miss whether I can pick up internet connection again even if connected to router. Tp link customer setvice(????) suggested contact BT which I did but this is def not the issue. I have literally spent hours trying to resolve.