Aircard 785 connection problems on iPad and MacBook Air

I have an Aircard 785 which was working perfectly with my iPad and MacBook Air. After being away and not using the 785 for one month it does not work as it did previously despite not making any changes to settings.

Whilst the 785 shows connection to IP with full signal, both devices will only operate for a few minutes (1-5) and then freeze up even though the devices as showing full signal too. The only way to get connection back is to restart the 785 which after 5+ times an hour becomes rather frustrating.

Any suggestions would be greatly appreciated.

Just a further note ... I have tried the SIM just in the iPad and it works perfectly!