Recently I purchased a Netcomm NL1901ACV Modem Router from PB tech to use at a site that currently doesn't have any fixed line internet but will have in the next 6 months. My intention was to run wifi off the cellular/sim card set up until fixed line internet became available, and then just use the cellular on demand if the fixed line dropped out. Link to model here: https://support.netcommwireless.com/product/nl1901acv

I managed to get it set up OK and it was reasonably straight forward, not the best interface but everything seemed to be running ok via cellular. It would appears that since it's been running the cellular connection drops out often. Its currently running a spark data sim. Wifi remains enabled, but when connected or reconnecting to it, presents on several devices as 'no internet connection' a full reboot of the modem is required for the cellular connection to come back to life, but again, this issues seem to rear its head every 6 - 10 hours. 

Has anyone else experienced this? Run out of idea's now but I suspect this shouldn't happen...