Internet connection issue

hi zyxel team. ,

I just received my NR5103EV2 mobile broadband router and facing issue with internet connection , some times when I connect to the network i have wifi without internet connection i have checked router settings from website its showing the router connection is up , after I restarted my router will have good internet connection this issue repeated every 1-2 days i have to restart the router please advise to fix it