OTAA Join Accept no longer received on multiple nodes after batteries were removed for some months

Hello champions,

I’m a little stumped and hoping for some guidance, please. I’ve had some nodes running perfectly on a farm for a number of months. At the beginning of this year, the nodes were ‘parked’ and stopped (batteries removed) for 1-2 months during the farming ‘off-season’. We now want to fire up the nodes again but we are not having a successful OTAA on all of the nodes we want to bring back to life.

Looking at Gateway console I can see Join Accepts are sent but it seems the nodes are not receiving these Accepts.

OTAA Join in TTN Console

The gateway (TTOG) appears to be behaving fine and processing uplinks (and downlinks) on other on-going nodes on the farm. It is just these nodes when were ‘parked’ for a few months which now can’t join via OTAA. I physically can’t get to the nodes either due to countrywide lockdown. Anybody with ideas on what the problem might be? Has it got something to do with the fact that these nodes were ‘offline’ for a few months? I can’t figure it out.

(To preempt some questions, the distance between nodes and gateway is not the issue, the nodes are placed about 800m away from the gateway, before being ‘parked’ uplinks were being sent at SF7. I’m getting this on all nodes which were ‘parked’ for a few months, not just one or two odd ones)

I would really appreciate anyone’s thoughts, it must be something really simple to suddenly affect all these nodes. (Tomorrow we’ll try rebooting the gateway but I feel we’re grabbing at straws.)

It would help if you could provide some more information on the nodes. What brand and type? How did you revive them after they”ve been parked for months?

Do you know at what SF the nodes start the OTAA? (The screenshot shows SF12, but they might have started with a better SF?)

Do you have access to any low-level logging on the TTOG? I wonder if ERROR: Packet REJECTED, unsupported RF power for TX - 24 could affect the TTOG as well. That problem started after something changed for V2 gateways being handled by something in V3, early this year. I don’t know the details. Maybe the TTOG has been using that route since much longer.

Oh, and is the gateway using 4G or a wired connection? (Maybe latency has increased, making downlinks arrive too late at the gateway? But then regular downlinks would not work either. Are you 100% sure that other downlinks work?)

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Dear @arjanvanb and @kersing

Thank you both very much for taking the time to reply to my post, your ideas spawned further troubleshooting avenues which I’m pleased to report yielded results. Arjan was on the money, latency had indeed increased.

My downlink test which I thought succeeded had indeed failed (it was late and I had to wait some 30 minutes for the next uplink and I had assumed it went through…) Another clue: All the existing live devices on the farm have ADR enabled and when I looked at them they were all transmitting on SF12 where usually they’re on SF7. I then viewed their logs and yup, the last few days they started ramping up from SF7 - SF12. This particular farm has a wired TTOG, and I started connecting the dots – in South Africa we rely on international internet traffic to reach TTN servers, an undersea cable snapped a few days ago and shortly after the data rates started increasing. A quick call to the farm’s ISP to reroute traffic and bang, all devices back to SF7 and OTAA joins going straight through… so there you have it… a broken sea cable.

On a separate note, thanks to you both for your inputs on this forum, I learn a lot from your posts.

KR
Grant

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