⛅ The Things Network Learn

Semtech UDP Packet Forwarder

The Semtech UDP Packet Forwarder is the first packet forwarder, connecting to servers through the Semtech UDP protocol. Although this protocol has several flaws, many gateways include a pre-compiled version of the packet forwarder, which makes it easy to test a gateway with this protocol.


Many gateways (Multitech Conduit, LORIX One…) include a pre-compiled version of this packet forwarder. For other gateways, the code is available online, and can be compiled with Semtech’s LoRa library.


When the packet forwarder starts, it looks in the current directory for a global_conf.json, a local_conf.json and a debug_conf.json. If debug_conf.json exists, the other files are ignored - otherwise, the parameters in local_conf.json override those in global_conf.json.


Before starting the packet forwarder, it is wiser to register the gateway in the console first, using its unique EUI.

EUI configuration

Once the registration is complete, add the gateway EUI in the local_conf.json:

  "gateway_conf": {
    "gateway_ID": "<Gateway EUI>"

Router configuration

After that, edit the global_conf.json file to point to the router. If you’re using the public community network, you will need to add the address of the router region - for example, for the EU region, it will be router.eu.thethings.network. Otherwise, it will be the hostname of your router - most of the time, it is just the hostname of your network.

Unless you’re running the network yourself on specific ports, the ports will be 1700 and 1700.

	"gateway_conf": {
		"server_address": "router.eu.thethings.network",
		"serv_port_up": 1700,
		"serv_port_down": 1700,

Router addresses

Region Router address
router.eu.thethings.network EU 433 and EU 863-870
router.us.thethings.network US 902-928
router.cn.thethings.network China 470-510 and 779-787
router.as.thethings.network Southeast Asia 923 MHz
router.as1.thethings.network Southeast Asia 920-923 MHz
router.as2.thethings.network Southeast Asia 923-925 MHz
router.kr.thethings.network Korea 920-923 MHz
router.jp.thethings.network Japan 923-925 MHz (with EIRP cap according to Japanese regulations)
thethings.meshed.com.au Australia 915-928 MHz
as923.thethings.meshed.com.au Australia (Southeast Asia 923MHz frequency plan)
ttn.opennetworkinfrastructure.org Switzerland (EU 433 and EU 863-870)


Click here to see troubleshooting steps for the Semtech UDP Packet Forwarder!