3G gateway is forwarding packets, but after some days TTN stops showing them until gateway is restarted

(Aitor Gartziandia) #1

Hi everyone,

I have a Multitech Conduit working as a packet forwarder, connected via ethernet cable to a router with a 3G connection to the internet.

The application seems to work fine for a while, but after a few days can’t see the packets sent by my mDots in the TTN console anymore. The gateway seems to be properly connected to TTN, as its “Last seen” field is updated every 30 seconds and using tcpdump I can see the status packets and the mDot packets being forwarded to TTN. But the packets are lost “somewhere”.

If I reboot the Conduit the packets start arriving TTN again and will work for a few days until the issue starts again.

I think this started when we changed the internet connection of the router from ADSL to 3G, but I’m very not sure. Can this change be related somehow with the trouble I’m having? Any other suggestion?

Thank you

(Arjan) #2

Yes, 3G latency might be the culprit. A lot of things to try in OTAA ok, 12h later I get denied, reboot gateway –> OK again …!? Also, changing IP addresses might make packets to be ignored for some (short) time.

(Aitor Gartziandia) #3

Hi, thanks for the response.

I have taken a look to the topic you mentioned and I think it was more about downlink packets not being transmitted because there where arriving to the gateway after RX2 closes, due to 3G latency. (Maybe I missed something).

In my case uplink packets are the ones being lost. How can this latency make the uplink packets to be lost? This latency would make the packets to arrive later, but still arrive. Am I wrong?

How can I find out if this is actually the cause or not?

Thanks so much!

(Arjan) #4

You’re right, my bad :frowning:

As for blocking, @htdvisser wrote in Slack June 9th:

That security measure indeed shouldn’t block a gateway for more than a minute after the old IP address “disappears”

(I think that blocking is only done when using the UDP/Semtech protocol packet forwarder.)

(Jac Kersing) #5

What software are you using to forward the packets to TTN?

(Aitor Gartziandia) #6


I am using the poly packet forwarder. I noticed I was using an old version so I have installed the newest one now.

(Aitor Gartziandia) #7

I reset de device to factory default settings, upgraded de firmware to lasta version and installed the new ttn packet forwarder. After all this, everything seems to be working correctly! I don’t know which was the cause of the issue but apparently disappered.

Thanks for your help!

(Arjan) #8

Are you using the new TCP protocol now?

Otherwise I feel it’s very a bit weird that tcpdump showed the packets, but it probably just cannot detect UDP problems. If it happens again, or to someone else, I guess one needs to compare the tcpdump output of succesful and troublesome packets.