USB OTG

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USB On-The-Go (USB OTG) is a supplementary standard to USB 2.0 that allows a device to switch between USB peripheral mode and host mode. Quectel Pi H1 supports USB OTG functionality. Through its onboard Type-C port, you can directly connect USB peripherals (such as USB flash drives, keyboards, mice, and network adapters) in host mode — without needing a PC for data reading or control operations.

This document describes how to use the USB Ethernet emulation (RNDIS) feature via the USB OTG interface to establish network connectivity and sharing between Quectel Pi H1 and a host computer.

Hardware interface

USB Ethernet Emulation Overview

USB Ethernet emulation (RNDIS) creates a virtual Ethernet link between the device and the host over a USB cable, enabling network communication without requiring an additional physical network adapter.

Quectel Pi H1’s default USB OTG gadget configuration includes RNDIS functionality (bundled with DIAG and ADB). After connection, a usb0 network interface appears on the Quectel Pi H1 side.

Once the connection is established, it can be used for:

• Remote login (SSH)

• File transfer (SCP / SFTP)

• Network sharing (host shares network to device, or device shares network to host)

• Debugging service access

Connecting to a Linux Host

Basic Connection Setup

1. Use a USB data cable to connect the Type-C port of Quectel Pi H1 to a USB port on the Linux host.

2. On Quectel Pi H1, verify that the usb0 interface exists, then enable and assign an IP address:

sudo ip link show usb0
sudo ip link set usb0 up
sudo ip addr add 192.168.0.5/24 dev usb0
sudo ip addr show usb0

1. On the Linux host, identify the newly added USB RNDIS network interface name (usually starts with enx), for example enx2a8b155b2e00:

ip link

1. On the Linux host, assign an IP address to this interface:

sudo ip link set enx2a8b155b2e00 up
sudo ip addr add 192.168.0.6/24 dev enx2a8b155b2e00

1. Replace enx2a8b155b2e00 with the actual interface name detected on your host.

2. Test connectivity:

ping 192.168.0.5

1. A successful response indicates the RNDIS connection has been established.

Sharing Network from Linux Host to Device

When the Linux host already has internet access via Ethernet or Wi-Fi, you can share the network with Quectel Pi H1.

Example parameters:

Role	Interface	IP Address
Linux WAN interface	enp11s0	—
Linux USB RNDIS interface	enx2a8b155b2e00	192.168.0.6
Quectel Pi H1 USB interface	usb0	192.168.0.5

To find the Linux host’s WAN interface, run ip route get 8.8.8.8 — the dev field in the output indicates the actual internet-facing interface.

Enable IPv4 forwarding on the Linux host:

sudo sysctl -w net.ipv4.ip_forward=1

Configure NAT forwarding on the Linux host:

sudo iptables -t nat -A POSTROUTING -o enp11s0 -j MASQUERADE
sudo iptables -A FORWARD -i enx2a8b155b2e00 -o enp11s0 -j ACCEPT
sudo iptables -A FORWARD -i enp11s0 -o enx2a8b155b2e00 -m state --state RELATED,ESTABLISHED -j ACCEPT

Replace enp11s0 and enx2a8b155b2e00 with your actual interface names.

Add a default route on Quectel Pi H1:

sudo ip route replace default via 192.168.0.6 dev usb0

Configure DNS on Quectel Pi H1:

sudo sh -c 'printf "nameserver 8.8.8.8\n" > /etc/resolv.conf'

Verify internet access from Quectel Pi H1:

ping 8.8.8.8
ping www.quectel.com

If you can ping a public IP but cannot resolve domain names, check the DNS configuration.

Sharing Network from Device to Linux Host

When Quectel Pi H1 already has internet access via another interface (such as Ethernet or cellular), you can share the network with the Linux host.

Example parameters:

Role	Interface
Quectel Pi H1 WAN interface	eth0
Quectel Pi H1 USB interface	usb0
Linux USB RNDIS interface	enx2a8b155b2e00

Run ip route get 8.8.8.8 on Quectel Pi H1 to determine the actual WAN interface.

Enable IPv4 forwarding on Quectel Pi H1:

sudo sysctl -w net.ipv4.ip_forward=1

Configure NAT forwarding on Quectel Pi H1:

sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
sudo iptables -A FORWARD -i usb0 -o eth0 -j ACCEPT
sudo iptables -A FORWARD -i eth0 -o usb0 -m state --state RELATED,ESTABLISHED -j ACCEPT

On the Linux host, point the default route to Quectel Pi H1:

sudo ip route replace default via 192.168.0.5 dev enx2a8b155b2e00

Verify internet access from the Linux host:

ping 8.8.8.8
ping www.quectel.com

If Quectel Pi H1 is connected via cellular or another interface, replace eth0 with the actual WAN interface.

Connecting to a Windows Host

Basic Connection Setup

1. Use a USB data cable to connect the Type-C port of Quectel Pi H1 to a USB port on the Windows host.

2. On Quectel Pi H1, verify that the usb0 interface exists, then enable and assign an IP address:

sudo ip link show usb0
sudo ip link set usb0 up
sudo ip addr add 192.168.7.1/24 dev usb0
sudo ip addr show usb0

3. On Windows, identify the newly added USB RNDIS adapter.

In Device Manager, you will see Remote NDIS Compatible Device under Network adapters. A new Ethernet connection will appear in Network Connections.

4. Configure the USB network adapter IP on Windows.

Open Network Settings, locate the newly added unidentified network, manually set the IP address to an address in the same subnet as Quectel Pi H1 (e.g., 192.168.7.2), and save.

5. Test connectivity:

ping 192.168.7.1

A successful response indicates the RNDIS connection has been established.

Sharing Network from Windows Host to Device

When the Windows host already has internet access via Ethernet or Wi-Fi, you can share the network with Quectel Pi H1 using Internet Connection Sharing (ICS).

1. Open the Network Connections page: Press Win + R, type ncpa.cpl, and press Enter.

2. Enable Internet Connection Sharing: Right-click the network adapter that currently has internet access (e.g., WLAN or Ethernet), select Properties → Sharing tab, check Allow other network users to connect through this computer’s Internet connection.

1. After enabling sharing, Windows typically sets the USB RNDIS adapter address to 192.168.137.1/24.

1. Reconfigure the usb0 IP on Quectel Pi H1 (must match the subnet assigned by Windows):

sudo ip addr flush dev usb0
sudo ip link set usb0 up
sudo ip addr add 192.168.137.2/24 dev usb0
sudo ip addr show usb0

1. Add a default route on Quectel Pi H1:

sudo ip route replace default via 192.168.137.1 dev usb0

1. Configure DNS on Quectel Pi H1:

sudo sh -c 'printf "nameserver 8.8.8.8\n" > /etc/resolv.conf'

1. Verify internet access from Quectel Pi H1:

ping 8.8.8.8
ping www.quectel.com

If you can ping a public IP but cannot resolve domain names, check the DNS configuration. If Windows did not set the USB RNDIS adapter to 192.168.137.1, use the actual IP shown and ensure Quectel Pi H1’s usb0 is in the same subnet.

Sharing Network from Device to Windows Host

When Quectel Pi H1 already has internet access via another interface, you can share the network with the Windows host.

Run ip route get 8.8.8.8 on Quectel Pi H1 to determine the actual WAN interface.

Enable IPv4 forwarding on Quectel Pi H1:

sudo sysctl -w net.ipv4.ip_forward=1

Configure NAT forwarding on Quectel Pi H1:

sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
sudo iptables -A FORWARD -i usb0 -o eth0 -j ACCEPT
sudo iptables -A FORWARD -i eth0 -o usb0 -m state --state RELATED,ESTABLISHED -j ACCEPT

If iptables is not found, install it via apt:

sudo apt update sudo apt install iptables

On Windows, set the gateway to Quectel Pi H1's IP (e.g., `192.168.7.1`).

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Verify internet access from Windows (it is recommended to temporarily disable other network connections to avoid interference):

ping 8.8.8.8
ping www.quectel.com

If Quectel Pi H1 is connected via cellular or another interface, replace eth0 with the actual WAN interface.

Troubleshooting

Symptom	Troubleshooting Steps
No usb0 interface on Quectel Pi H1	Verify the Type-C cable supports data transfer; run sudo qusb showpid to check if the USB composition mode includes RNDIS or NCM
No new network adapter on the host	Replug the cable and check dmesg | tail -n 50 (Linux) or Device Manager (Windows) to see if USB Ethernet / RNDIS device is detected
Can ping public IP but cannot resolve domain names	Check /etc/resolv.conf or system DNS configuration
Still cannot access the internet after configuring NAT	Verify the default route points to the peer USB adapter address; run iptables -t nat -L -n -v to check if forwarding rules are active