Hi @Mjrizal, welcome to the Community!

Sorry to hear your Internet isn't working properly. No worries though, I'll do my utmost to help you as much as possible. Internet is extremely important. You should have a solid connection too! First we'll check the most important things:

1) Check which lights are lit on the modem. Does WAN or Internet not light up? Then disconnect the modem from the power for 10 seconds by unplugging the power cord. 

2) Does it concern Wifi and is the WLAN light not on? Then press the button "WLAN / WPS / Wireless / Wifi" until the light comes on.  

3) Are the lights on, but you are not connected? Then connect your computer directly to the modem with an internet cable on port 1 or 2 of the modem. If you have a Zyxel modem, it doesn't matter which port you connect the computer to.  

Does it still not work after this? Take a look at our special topic. This allows you to solve common problems.

If I can help you with something else, please don't hesitate to ask. I'd be more than happy to help you out. Stay safe and have an amazing weekend!