This article provides a guide on troubleshooting and configuring your Zyxel device. It reviews the front panel LEDs, explaining the meaning of different colours and LED states to help users diagnose problems effectively. The guide also covers logging into the web interface to manage the Zyxel device, including steps for a factory reset, working with SIM card PINs, and manually entering APN settings when necessary. The manual also provides instructions on how to update the firmware.

Introduction to the Unit

You can determine what is wrong with your device by looking at the front panel:

Login to Web GUI

• Ensure your Zyxel Device hardware is connected correctly (refer to the Quick Start Guide).  
• Launch your web browser. If the Zyxel Device does not automatically re-direct you to the login screen, go to http://192.168.1.1. 
• A password screen displays. Select the language you prefer (upper right). 
• To access the Web Configurator and manage the Zyxel Device, type the default username admin and the randomly assigned default password (see the Zyxel Device label) in the Login screen and click Login. If you have changed the password, enter your password and click Login. 

Note: You will be asked to change the password the first time you enter it. The new password must contain at least one uppercase letter, one lowercase letter, and one number.

The Connection Status screen appears. Use this screen to configure basic Internet access, wireless settings, and parental control settings.

On this page, you can check system information, change WIFI settings, check signal strength and change LAN settings. All other functionality is available by clicking on the menu in the upper right side of the screen

Troubleshooting - Reset Device

Firstly, if you haven't made many changes to the configuration of the unit, I would start with a reset of the unit - by pressing and holding the button for 20 seconds:

This would reset the device to factory reset, where your WiFi and admin password will go back to the factory default, which you can find under the device.

Troubleshooting - SIM PIN Code

If you have a sim card with a PIN code, you need to enter the PIN code into the device.

If you don't know if you have a PIN code, try inserting the SIM card into your mobile phone. If it doesn't ask for a PIN code, you don't have one.

Note: Entering the wrong PIN code 3 consecutive times locks the SIM card, after which you need a PUK (Personal Unlocking Key) from the service provider to unlock it.

Login to the unit by connecting your computer to the WiFi of the LTE3301-PLUS and enter http://192.168.1.1 using your browser and use the username admin and password 1234:

If you get problems, use this article: Accessing your router via Web GUI

Go to Configuration -> Network Setting -> Broadband -> Cellular SIM -> Enter PIN-code

 If you don't want the device to require a PIN every time you restart the unit, set the PIN-code Request function to "Disable" and hit apply.

After you have entered the PIN Code in the box, press "Apply".

Troubleshooting - Enter APN settings manually

If you are still having problems after resetting the unit, you might need to enter the APN information of your SIM card manually in the device. You can find the APN information by calling your service provider (ISP). 

Go to -> Network Setting -> Broadband -> Cellular WAN -> Click "APN Manual Mode."

When you click on manual, you will find the APN settings, which you can enter manually by inserting the information that your service provider can provide.

Note: You can also try using another SIM card in the unit to see if the One you have is faulty. You can also insert the LTE SIM card into a mobile phone and see if you get a signal.

Troubleshooting -  Firmware Upgrade

Upgrading firmware to the latest version could help with your issue because your device's software is not running the latest modifications.

• Click on this link below to download the latest firmware
  LTE3301-PLUS Download Link
• Extract the zipped file you have downloaded with the built-in extractor of your operative system (or Winzip, 7-zip)
• Login to the Web GUI of the LTE3301 using this guide: Accessing your router via Web GUI
• Go to Maintenance-> Firmware upgrade and then click on Browse... and choose the .bin file you have extracted

Click on upload and let the firmware be updated; this can take up to 3 minutes (DO NOT TURN OFF THE DEVICE).

Port Forwarding

The most common usage of port forwarding is when you want to reach a NAS (192.168.1.34) or a server in your network on the HTTPS (443) port, then the request coming from the PC (Originating IP 94.33.45.234) at work, have to be forwarded to the correct device (192.168.1.34) in your home when a request is coming on the port 443:

A big misconception is that you are opening a port on your router, but that's not true. You are forwarding a port to a device in your network to be able to access it. It is important that you either limit the source IPs (Originating IP) to the trusted IPs connecting from the internet, or create really good security on the device/server you port forward to.

What does it mean?
Status: Is the port forward active or not? 
Service Name: The name of the port forwarding rule
Originating IP: The source IP (where the public IP is coming from on the internet site)

WAN Interface: What public WAN interface to be triggered when a port forwarding is happening
Server IP address: The device in your network to which the router is going to forward the traffic to
Start Port: What external starting port do you want to forward
End Port: What external ending port do you want to forward (if it's only one port, e.g. HTTPS 443, then select 443 on both the start port and the end port).
Translation Start Port: What internal starting port do you want to forward
Translation End Port: What internal ending port do you want to forward (if it's only one port, e.g. HTTPS 443, then select 443 on both the start port and the end port). This is in most cases configured as the same as the start port and end port