4012 T6 LTS-4G EN
Keywords
FriendlyElec NanoPC T6 LTS, RK3588, 4G LTE, ZTE CAT4 4G, Qualcomm 4G, FriendlyWrt, OpenWrt, Ubuntu, Debian, Android
I. Introduction
The T6 LTS-4G is an USB 4G LTE module specifically designed for the FriendlyElec NanoPC T6 LTS board, expanded through its M.2 M-key interface. The adapter board features an irregular shape that does not occupy the WiFi module's position and is fully enclosed within the metal casing. 4G LTE uses either a ZTE CAT4 4G or Qualcomm 4G/NL668-EAU/NL668-AM solution, with an onboard Nano SIM card slot. The 4G antenna adopts an IPEX 1 interface with a dual-antenna configuration.
FriendlyElec's FriendlyWrt, Ubuntu OS, Debian OS and Android (limited to ZTE's solution) support driver-free and auto-identification of 4G.
NanoPC-T6 LTS (as "T6") is a one-for-all high performance open source platform for edge computing, designed and developed by the FriendlyElec team. It has two 2.5G Ethernet ports. It is based on Rockchip's RK3588. In summary, T6 is well suited for enterprise customers to develop mini machine vision systems with multiple Ethernet ports and for embedded system hobbyists to explore and implement prototype designs.
II. Hardware Spec
The T6 LTS-4G utilizes the M.2 M-key of the PCIe on the development board to expand USB ports for connecting a 4G module.
1) On-board imported DC-DC power supply.
2) 1*4G LTE.
3) 1*Nano SIM card slot.
4) 2*IPEX 1 antennas. Reserve one IPEX 1 GPS antenna connector (for Qualcomm 4G-GPS).
5) 2*LEDs, one is the power indicator, one is the 4G network registration indicator.
6) Size: 54mm*81mm. PCB certified by UL and ROHS.
III. Work with FriendlyWrt
Test using the FriendlyWrt version: rk3588-sd-friendlywrt-24.10-20250811.img.gz.
This documentation demonstrates booting the OS from a TF card. The OS is configured by default with eth0 as WAN and eth1 as LAN.
When 4G is not connected, ETH1 on the casing is identified as eth0 and serves as WAN, ETH2 is identified as eth1 and serves as LAN:
3.1 Test 4G LTE
With 4G enabled, no configuration is needed. At this point, the eth0 in the OS is configured for 4G, meaning 4G is automatically recognized and set as WAN by default. The ETH1 on the casing is recognized as eth1 and automatically configured as LAN. The ETH2 on the casing is recognized as eth2 and remains unconfigured, it can be set up as either LAN or WAN.
Connect the Ethernet (labeled "ETH1" on the casing) to the PC. After the OS starts, open the web browser on the PC, enter 192.168.2.1 to access the backend. The default username is root and the default password is password:
Click on "Services - Terminal", then log in to the terminal. The default username is root, and the password is password:
Execute ifconfig -a, and the result is as follows:
▶ ZTE CAT4:
▶ Qualcomm 4G-GPS/NL668-EAU/NL668-AM:
eth0 is the 4G LTE interface and has successfully obtained an IP address.
We pinged both the IP and the domain, and both were successful, indicating that the 4G LTE is functioning properly:
At this point, the network card properties of the LAN port (labeled "ETH1" on the casing) are displayed as follows:
Open https://test.ustc.edu.cn/ in a PC browser to perform a speed test, with the following results:
▶ ZTE CAT4:■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■▶ Qualcomm 4G-GPS/NL668-EAU/NL668-AM:
Note: Network speed tests are affected by the network environment and testing methods. Please refer to the actual speed, as this test is for reference only.
3.2 Configure Ethernet2 as LAN
At this point, the eth2 (labeled "ETH2" on the casing) is unconfigured. Here, we will demonstrate configuring it as a LAN port. The final setup will use 4G as the WAN and the two Ethernet ports as LANs.
Click "Network - Interfaces", click on "Devices", then click "Configure..." next to "br-lan":
In the pop-up window under "Bridge Ports", click the drop-down arrow, select "eth2", and then click "Save":
Automatically return to the previous page, click "Save & Apply":
So we have also configured eth2 as a LAN.
3.3 Use AT commands
Generally, a 4G module only needs to maintain a normal internet connection. If additional operations are required (such as checking antenna signal or setting APN), AT commands can be used. The operation method is as follows.
3.3.1 Install the serial port software
Before using AT commands, you need to install the serial port software minicom. Click "System - Software", then click the "Update lists..." button:
Close the prompt window after the update is complete:
In the box under "Download and install package", enter "minicom" and then click "OK":
Click "Install":
After installation, click "Dismiss":
Then click on "Services - Terminal" to log in to the terminal.
3.3.2 Work with ZTE CAT4
Execute:
ls /dev/ttyUSB*
At this point, you should see four devices generated under the dev directory: ttyUSB0 - ttyUSB3.
By default (when the USB ports are not connected to any devices other than the keyboard and mouse), the AT command serial port is ttyUSB0.
Open the AT command serial port through minicom:
minicom -D /dev/ttyUSB0
The first time you enter an AT command, there may be no echo. If you then input the command at and press Enter, and it returns "OK," it indicates that everything is working properly. If you need to check the echo, please type the command: ate1, then press Enter. After that, you can continue to type other commands and see the inputs.
Use AT+CPIN? to check if the SIM card is properly inserted and recognized.
Use AT+CSQ to check the signal strength. The first value ranges from 0 to 31, and a value above 25 indicates good signal quality.
Use AT+COPS? to check the status of the registered network. The content within the double quotes is the operator code, and the last digit represents the network mode, where 7 stands for 4G.
3.3.3 Work with Qualcomm 4G-GPS/NL668-EAU/NL668-AM
Execute lsusb in the terminal, and the result is as follows:
Record the ID value of the 4G module: 05c6 90b6.
Use the following command to open the ttyUSB serial port, where the value after echo is the ID recorded above:
modprobe option
sh -c 'echo 05c6 90b6 > /sys/bus/usb-serial/drivers/option1/new_id'
After executing the above two commands, execute:
ls /dev/ttyUSB*
At this point, you should see three devices generated under the dev directory: ttyUSB0 - ttyUSB2. If the first two commands are executed incorrectly, these three devices cannot be properly generated, and the two commands need to be re-executed correctly:
By default (when the USB ports are not connected to any devices other than the keyboard and mouse), the AT command serial port is ttyUSB0.
For subsequent operations, please refer to the section on installing the serial port tool and ZTE CAT4 operations, which will not be repeated here.
IV. Work with Ubuntu OS
Test using the Ubuntu OS flashing package for T6 development board, version: rk3588-sd-ubuntu-noble-desktop-6.1-arm64-20250811.img.gz.
This documentation demonstrates booting the OS from a TF card.
4.1 Work with ZTE CAT4
Without connecting the Ethernet cable, execute lsusb in the terminal, and the result is as follows:
Execute ifconfig -a to view the network parameters as follows:
We ping the IP and the domain name. The IP ping is successful, but pinging the domain name returns an error:
At this point, the DNS switching software udhcpc needs to be installed.
Please connect any Ethernet port to the upstream router, then execute in the terminal:
sudo apt install udhcpc
After installation, unplug the network cable and execute:
sudo udhcpc -i eth2
After the execution was completed, both the IP and domain name were successfully pinged, indicating that the ZTE CAT4 is functioning properly:
4.2 Work with Qualcomm 4G-GPS/NL668-EAU/NL668-AM
Without connecting the Ethernet cable, execute lsusb in the terminal, and the result is as follows:
Execute ifconfig -a to view the network parameters as follows:
We pinged both the IP and the domain, and both were successful, indicating that the Qualcomm 4G-GPS/NL668-EAU/NL668-AM is functioning properly:
Open https://test.ustc.edu.cn/ in a PC browser to perform a speed test, with the following results:
▶ ZTE CAT4:■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■▶ Qualcomm 4G-GPS/NL668-EAU/NL668-AM:
Note: Network speed tests are affected by the network environment and testing methods. Please refer to the actual speed, as this test is for reference only.
V. Work with Debian OS
Test using the Debian OS flashing package for T6 development board, version: rk3588-sd-debian-bullseye-desktop-6.1-arm64-20250811.img.gz.
This documentation demonstrates booting the OS from a TF card.
5.1 Work with ZTE CAT4
Without connecting the Ethernet cable, execute lsusb in the terminal, and the result is as follows:
Execute ip addr to view the network parameters as follows:
eth0 and eth1 are two 2.5Gbps Ethernet interfaces, and eth2 is ZTE CAT4, which has successfully obtained an IP address.
We ping the IP and the domain name. The IP ping is successful, but pinging the domain name returns an error:
At this point, the DNS switching software udhcpc needs to be installed.
Please connect any Ethernet port to the upstream router, then execute in the terminal:
sudo apt update
Execute:
sudo apt install udhcpc
After installation, unplug the network cable and execute:
sudo udhcpc -i eth2
After the execution was completed, both the IP and domain name were successfully pinged, indicating that the ZTE CAT4 is functioning properly:
5.2 Work with Qualcomm 4G-GPS/NL668-EAU/NL668-AM
Without connecting the Ethernet cable, execute lsusb in the terminal, and the result is as follows:
Execute ip addr to view the network parameters as follows:
eth0 and eth1 are two 2.5Gbps Ethernet interfaces, and eth2 is Qualcomm 4G-GPS/NL668-EAU/NL668-AM, which has successfully obtained an IP address.
We pinged both the IP and the domain, and both were successful, indicating that the Qualcomm 4G is functioning properly:
Open https://test.ustc.edu.cn/ in a PC browser to perform a speed test, with the following results:
▶ ZTE CAT4:■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■▶ Qualcomm 4G-GPS/NL668-EAU/NL668-AM:
Note: Network speed tests are affected by the network environment and testing methods. Please refer to the actual speed, as this test is for reference only.
VI. Work with Android
Test using the Android flashing package for T6 development board, version: rk3588-sd-android14-20251010.img.gz.
Note: The FriendlyElec's Android only supports ZTE CAT4 and is not compatible with other 4G modules.
This documentation demonstrates booting the OS from a TF card.
Without connecting the network cable, power on and start the OS. You can directly access the internet, and a successful connection indicator will appear in the status bar at the top-right corner of the desktop, as shown in the figure below:
Open https://test.ustc.edu.cn/ in Chrome to perform a speed test, with the following results:
Note: Network speed tests are affected by the network environment and testing methods. Please refer to the actual speed, as this test is for reference only.
If you need to check the detailed status of the network, you can download and install the terminal software Termux for viewing. The download link is:
http://www.mcuzone.com/wiki/3007_CM4_4G_Mini/termux_1020.apk
Before installation, you need to enable "Install unknown apps" in the Settings:
After installing Termux, open the software and execute ifconfig -a in terminal:
We pinged both the IP and the domain, and both were successful, indicating that the ZTE CAT4 is functioning properly:
7.1 Use AT commands
The usage of the AT command is the same in Ubuntu OS and Debian OS. This chapter explains it based on the Ubuntu OS. The operations are as follows:
▶ ZTE CAT4:
Install the serial port software minicom:
sudo apt install minicom
Execute:
ls /dev/ttyUSB*
At this point, you should see four devices generated under the dev directory: ttyUSB0 - ttyUSB3.
By default (when the USB ports are not connected to any devices other than the keyboard and mouse), the AT command serial port is ttyUSB0.
Open the AT command serial port through minicom:
sudo minicom -D /dev/ttyUSB0
The first time you enter an AT command, there may be no echo. If you then input the command at and press Enter, and it returns "OK," it indicates that everything is working properly. If you need to check the echo, please type the command: ate1, then press Enter. After that, you can continue to type other commands and see the inputs.
Use AT+CPIN? to check if the SIM card is properly inserted and recognized.
Use AT+CSQ to check the signal strength. The first value ranges from 0 to 31, and a value above 25 indicates good signal quality.
Use AT+COPS? to check the status of the registered network. The content within the double quotes is the operator code, and the last digit represents the network mode, where 7 stands for 4G.
▶ Qualcomm 4G-GPS/NL668-EAU/NL668-AM:
Before using AT commands with Qualcomm 4G-GPS/NL668-EAU/NL668-AM, the serial port must first be opened. Execute lsusb in the terminal, and the result is as follows:
Record the ID value of the 4G module: 05c6 90b6.
Use the following command to open the ttyUSB serial port, where the value after echo is the ID recorded above:
sudo modprobe option
sudo sh -c 'echo 05c6 90b6 > /sys/bus/usb-serial/drivers/option1/new_id'
After executing the above two commands, execute:
ls /dev/ttyUSB*
At this point, you should see three devices generated under the dev directory: ttyUSB0 - ttyUSB2. If the first two commands are executed incorrectly, these three devices cannot be properly generated, and the two commands need to be re-executed correctly:
By default (when the USB ports are not connected to any devices other than the keyboard and mouse), the AT command serial port is ttyUSB0.
For subsequent operations, please refer to the ZTE CAT4 section starting from the "Install the serial port software minicom", which will not be repeated here.
7.2 Common AT commands
Common AT commands:
1. Check if the SIM card is detected:
at+cpin?
Return ready to indicate the card has been recognized, if return error, you need to check the hardware.
2. Check antenna signal quality:
at+csq
Return values between 26 and 31 indicate a good signal, with 31 representing a full signal strength; return values between 20 and 25 indicate a barely acceptable signal; return values below 20 indicate a poor signal or that the antenna might not be connected.
3. Check network registration status:
at+cops?
Normally, it should return the network supporter's code: 7, where 7 represents 4G.
Note: The above command at+csq should not include a question mark, while the other two commands require a question mark.
4. View the SIM card's IMEI code:
at+cgsn
5. Reset 4G module (Sometimes, if you reinsert the SIM card, hot swapping may not work; in such cases, you can use this reset command to reset the module.):
at+reset
6. Disable radio frequency:
at+cfun=0
Enable radio frequency:
at+cfun=1
The two commands mentioned above can be used in pairs to allow the module to re-register with the network without restarting the 4G module.
7.3 Modify the 4G IP address
If the default 4G IP address assigned at the factory conflicts with the IP address being used by the user, or if there is a need to modify the IP address, you can change the 4G module's IP.
ZTE CAT4, Qualcomm 4G-GPS/NL668-EAU/NL668-AM:
Set the 4G module's IP to directly obtain a public IP. Please execute the AT command:
Set the IP to public: AT+GTIPPASS=1
Set the IP to private: AT+GTIPPASS=0
Check whether the current IP is a public or private IP: AT+GTIPPASS?
After modifying the IP, a power cycle reboot is required for the changes to take effect.
7.4 FAQ
▶ What should I do if I have to execute udcpc every time the OS starts?
Q: For a 4G module that needs to connect to the internet by modifying the DNS server, it can connect normally after installing and executing udcpc. However, udcpc needs to be execute every time the OS reboots. If you want to automatically connect to the internet via the 4G network upon startup, what should I do?
A: You can set a fixed DNS address in the system file by following these steps:
Install the text editor nano, execute in the terminal:
sudo apt install nano
Execute the following command to open the resolv.conf file in the terminal:
sudo nano /etc/resolv.conf
Check if the address after "nameserver" (in the red box above) is the correct DNS address. If not, change it to the DNS address of the SIM card (usually its gateway address) or a common DNS address (such as 114.114.114.114).
After the modifications were completed, we successfully pinged the domain:
However, after the OS reboots, the DNS settings in the resolv.conf file will be reverted to the default addresses. So if you need the 4G module to automatically connect to the internet on startup, you also need to modify the permissions of the resolv.conf file. Because /etc/resolv.conf is actually a symbolic link, the resolv.conf file needs to be re-created to modify its permissions. The method is as follows:
Execute the following command in the terminal:
sudo mv /etc/resolv.conf /etc/resolv.conf.link
sudo nano /etc/resolv.conf
This re-creates the resolv.conf file. Enter the DNS address in this new file, for example:
nameserver 114.114.114.114
Save and exit, then execute:
sudo chattr +i /etc/resolv.conf
After completing the above steps, the content of the resolv.conf file will no longer change even after restarting the OS.
VIII. NanoPi 4G and WiFi selection guide
| No. | NanoPi Model | CPU | Ethernet | Built-in 4G | Built-in WiFi | USB | Notes |
|---|---|---|---|---|---|---|---|
| 1 | R2S PLUS | RK3328 | 2 | CM4 CAT4/ CM4 Qualcomm 4G/NL668-EAU/EU/AM-USB | RTL8822(SDIO) | 2 | 1 USB left, after using 4G |
| 2 | R3S | RK3566 | 2 | CM4 Qualcomm 4G/NL668-EAU/EU/AM-USB | None | 1 | No USB after using 4G |
| 3 | R5C | RK3568B2 | 2 | CM4 Qualcomm 4G/NL668-EAU/EU/AM-USB | MT7922/8822CE | 2 | 1 USB left, after using 4G |
| 4 | R5S LTS | 3 | CM4 Qualcomm 4G/NL668-EAU/EU/AM-USB | External MT7922/8822CE | 2 | 1 USB left ,after using 4G | |
| Qualcomm 4G/NL668-EAU/EU/AM/ZTE CAT4-M.2 | None | ||||||
| 5 | R6C | RK3588S | 2 | CM4 Qualcomm 4G/NL668-EAU/EU/AM-USB | External MT7922/8822CE | 2 | 1 USB left, after using 4G |
| Qualcomm 4G/NL668-EAU/EU/AM/ZTE CAT4-M.2 | None | ||||||
| 6 | M6 | 1 | Qualcomm 4G/NL668-EAU/EU/AM/ZTE CAT4-M.2 | MT7922/8822CE | 3 | ||
| 7 | R6S | 3 | CM4 CAT4/Qualcomm 4G/NL668-EU/EAU / AM/ZTE CAT4-USB | None | 2 | 1 USB left ,after using 4G | |
| 8 | T6 (Ver. 2301) | RK3588 | 2 | MiniPCIe CAT4/Qualcomm 4G/NL668-EU/EAU/AM/ZTE CAT4 | MT7922/8822CE | 1 | |
| 9 | T6 LTS | CM4 CAT4/Qualcomm 4G/NL668-EU/EAU/AM/ZTE CAT4-USB | MT7922/8822CE | 3+2 | 3+1 USB left, after using 4G | ||
| 10 | R4S | RK3399 | 2 | CM4 CAT4/Qualcomm 4G/NL668-EAU/EU/AM-USB | None | 2+1 | |
| 11 | R4SE | CM4 CAT4/Qualcomm 4G/NL668-EAU/EU/AM-USB | None | 2 | 1 USB left ,after using 4G | ||
| 12 | M5 | RK3576 | 2 | Qualcomm 4G/NL668-EAU/EU/AM/ZTE CAT4-M.2 | SDIO | 2 | |
| 13 | Zero2 | RK3528A | 1 | External CM4 CAT4/ Qualcomm 4G/NL668-EAU/EU/AM-USB | MT7922/8822CE | 1 | No USB after using 4G |
IX. Summary
We only introduce the usage and operations for T6 LTS-4G, without covering the operations and software system specific to the NanoPC T6 LTS development board itself. For information about the NanoPC T6 LTS development boards, please visit the FriendlyElec's website:
https://wiki.friendlyelec.com/wiki/index.php/NanoPC-T6
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