❓ Help ZyXEL NBG-417N cannot connect using SUN Cellular Postpaid Sim need help for configuration!

[Southside]

Here's the thing we have a Zyxel NBG-417N Wireless N-lite Moe Router that has a sim slot. I did some setup and sometimes the WiFi i made Connects and about 10 minutes it DISCONNECTS to Homescreen of the Config it says SUN and *Connected* but no internet connection even if i use lan or the wifi. Help Guys! Thanks