Class C downlinks failing from changing rx2 data rate

comori
Fri, 09 May 2025 19:49:07 +0000
The Things Stack v3

Hi all,

Setup:

TTS Cloud Standard

RAK Gateway

RAK End Node

Situation:
Im running into a recurring sporadic problem where Class C devices stop receiving downlinks. I believe I’ve narrowed the issue to the Network Server scheduling the downlink using a different data rate than what’s set. Currently, I have the desired rx2 data rate set to 12, and ADR is turned off on both the Network Server and the end device.

When I first start the device, it is able to receive downlinks, but after a certain amount of time (say 24-48 hours) the Network Server changes the data rate. I am able to verify that the data rate changes by looking at the debugging logs of my gateway. See an example below where dr=13 instead of 12

Fri May  9 19:46:13 2025 user.debug basicstation[3968]: [LOG:DEBU] rrd_statistic_down-421 downlinkTqByAirtime: dr=13, timeonair=13, tm=1746819973
Fri May  9 19:46:13 2025 user.debug basicstation[3968]: [LOG:DEBU] rrd_statistic_down-423 downlinkTqByPkt: dr=13, tm=1746819973
Fri May  9 19:46:13 2025 user.debug basicstation[3968]: [AIO:DEBU] [5|WS] > {"msgtype":"dntxed","seqno":70,"diid":70,"DR":13,"Freq":926900000,"DevEui":"00-00-00-00-00-00-00-01","rctx":0,"xtime":41658301258945080,"txtime":5521759.889923,"gpstime":0}
Fri May  9 19:46:13 2025 user.info basicstation[3968]: [S2E:INFO] TX ::1 diid=70 [ant#0] - dntxed: 926.9MHz 26.0dBm ant#0(0) DR13 SF7/BW500 frame=A0CED4FE2726C5030D121E49..6093AB7F (20 bytes)
Fri May  9 19:46:13 2025 user.debug basicstation[3968]: [S2E:DEBU] Tx done diid=70

Another issue is that this is sporadic, so somewhere from 25% - 50% of devices that I deploy run into this issue.

Any insight to this issue?

EDIT: to clarify, I am referring to downlinks I am initiating, not as a result of a confirmed uplink.

32 posts - 4 participants