LSE01 nodes stopped working at certain gateways

Dear all,

I noticed a strange interaction between some Dragino LSE01- nodes and Dragino gateways. At a hilly field site (about 1km²) 60 LoRa nodes are installed. Forty nodes are buried at a depth of 35 cm to allow normal agricultural use of the area and 20 nodes are from Dragino (LSE01) for mobile measurements of upper soil moisture. To pick up all signals especially in periods with high soil moisture and/or canopy height two Dragino gateways (DLOS8) in a distance of about 500m were installed.

For unknown reasons some of the LSE01 stopped transmitting after months and we are unable to join them again. They did not stop at the same time. There are days to weeks in between. There is another Gateway (LG308) about 8km (linear distance) away, which sometimes receives also some Lora frames from the site. However, if we bring the LSE01 near to this gateway, no join is received either.

We sent the activated (but not re-joined?) nodes to the office (180km away) by mail. The strange thing is that they start sending within an hour of arrival, with no user intervention. The Gateway in the office is a Dragino Pico Station. We are using Webhooks to receive the uplink messages from TTN and can see, if the nodes send regular or not.

I suppose the problem is somehow related to the gateways, since the nodes are working with the office gateway (the nodes were never connected to the office gateway before).

Does a LoRa gateway do more than just transmit data frames between the nodes and the application server (TTN) and vice versa?

What could be the reason for this behavior (we observed that for five nodes until now)?
Could it have something to do with the frequencies (we use EU686-nodes, selected in the gateway as well) - maybe the join request is not received on the right frequence?

I am grateful for any advice!

No. That is it.

HOWEVER, I found it sometimes helps to reboot gateways. Somehow some older Dragino gateways seem to stop transmitting downlinks and after a reboot everything again works as expected.

Dear Jac,
thank you very much for your answers.

Thanks for confimation.

We wonder why only a few nodes are affected while the others are working fine? There are three gateways that suddenly stopped sending downlinks?

A reboot (always) seems to be a good idea. We will give it a try.

May be just one gateway stopped sending downlinks and the TTN backend is using that one for the nodes that are affected?

Dear Jac,

we replaced the nodes with new ones some month ago and they work perfectly. Now, after a long time, I have one of the old nodes back in the office. I noticed that only a few hairs of the shielding of the antenna cable were still clipped to the tiny socket. The core wire was not connected anymore.
I found that the node is working without antenna in the office quite well (not recommended to test with new nodes, Lora-modem could be damaged). However, it would certainly not work in the field. I suspect that the antenna cable was damaged when the node’s battery was replaced. Also, it could be that the connection to the antenna gets better or worse due to vibrations during transport, which could explain the behaviour.

I know this is just a wild guess, but it sounds reasonable to me :wink:

Unfortunately, rebooting the gateways is still an issue. Sometimes only the status information of the gateway is transmitted, but no LoRa-messages. In TTN the gateway is listed as «connected». Only a restart solves the problem. However, that’s another topic …

Many thanks for your help so far!

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