V3 ADR always resets to SF7

TTN V2 to V3 Upgrade
1

Dear TTN Community,

I have started to migrate my devices to the v3 stack.
There were no problems at first and everything works as expected.
About my nodes, I use the IMST IM881A for LoRaWAN. (MAC 1.0.2)
However, I have problems with the nodes that have a high distance to the gateways.The SF factor is slowly increased by the node. With v2, some stayed at SF9. Others at SF10-12. Now the SF factor is increased again normally. But whenever the first packets arrive with e.g. SF10, it is reduced again to SF7 by ADR command. And then I get huge data gaps. Every time something arrives again, but the ADR command resets the DR to 5.
Why does the v3 stack do that? The Network Server must see on the counter that the last 100 packets or more have not arrived. Why does it always set to SF7 again?
Does anyone have an idea what the problem is and how I can change it?

2

It doesn’t look at any loss of uplinks, it just works off the RSSI & SNR.

Can you give us some figures on the signal whilst I look for the link to the code used.

3

How many packets do you send per hour and do you use confirmed uplinks ?

4

Here’s how it’s calculated:

5

The value in line 63 of the code doesn’t seem to be plausible. But imho this is not the reason for the reduction to SF7.

6

I use unconfirmed uplinks. 5-10 per hour.
I can’t say for sure if this case was really reduced to SF7, because I didn’t record the console. But I have seen it before, although the receiving values were not so good.
The ADR from the v3-stack is unfortunately bad in my experience and should be adjusted.I measure meteorological data and these should be more or less complete.

Found another case where it is the same.

This is how it looks then, on 03/28 I turned off my TTIG.
Then I waited, but ADR comes to no satisfactory settings. Almost everything is lost

datetime                 , id   ,f_cnt, gateway,         RSSI,   SNR,  SF,
(2021, 4,  1,  3,  9, 54), 13831, 671, 'packetbroker', -117.0, -15.2,  10, 
(2021, 3, 30, 23, 21, 44), 13831, 501, 'packetbroker', -118.0, -13.2,  11, 
(2021, 3, 30, 23, 14, 44), 13831, 500, 'ifm-imst',     -120.0, -12.75, 11,
(2021, 3, 30, 23,  7, 44), 13831, 499, 'ifm-imst',     -121.0, -13.5,  11, 
(2021, 3, 30, 22, 53, 43), 13831, 497, 'ifm-imst',     -119.0, -13.75, 10,
(2021, 3, 30, 22, 39, 43), 13831, 495, 'ifm-imst',     -120.0, -14.25, 10,
(2021, 3, 30, 22, 32, 44), 13831, 494, 'ifm-imst',     -121.0, -14.0,  10, 
(2021, 3, 30, 22, 25, 43), 13831, 493, 'packetbroker', -117.0, -14.5,  10, 
(2021, 3, 30, 21, 30, 43), 13831, 485, 'packetbroker', -118.0, -12.0,  10,
(2021, 3, 30, 21,  3, 23), 13831, 481, 'ifm-imst',     -120.0, -16.0,  10, 
(2021, 3, 30, 20, 49, 43), 13831, 479, 'packetbroker', -117.0, -14.8,  10, 
(2021, 3, 30, 20, 29, 23), 13831, 476, 'ifm-imst',     -118.0, -14.0,  10, 
(2021, 3, 30, 19, 42, 43), 13831, 469, 'packetbroker', -117.0, -11.5,  10, 
(2021, 3, 30, 19, 28, 43), 13831, 467, 'packetbroker', -118.0, -12.0,  10,
(2021, 3, 29, 18,  2, 43), 13831, 306, 'packetbroker', -111.0, -12.2,   9, 
(2021, 3, 29, 17, 47, 23), 13831, 304, 'packetbroker', -111.0, -13.5,   9, 
(2021, 3, 29, 17, 41, 23), 13831, 303, 'packetbroker'  -116.0, -11.0,   9, 
(2021, 3, 28, 20, 15, 13), 13831, 174, 'packetbroker',  -72.0,  7.75,   7, 
(2021, 3, 28, 20,  4, 33), 13831, 173, 'packetbroker',  -75.0,   9.5,   7,

This was not the case with TTN-v2. ADR adapted more slowly, but actually about 50% of the packets arrived after successful adaptation.
Can I use ttn-lw-cli to add my own values?

ttn-lw-cli end-devices set <app-id> <dev-id> --mac-state.desired-parameters.adr-data-rate-index
ttn-lw-cli end-devices set <app-id> <dev-id> --mac-state.desired-parameters.adr-tx-power-index
ttn-lw-cli end-devices set <app-id> <dev-id> --mac-state.desired-parameters.adr-nb-trans
7

I can confirm the problem!

In my case the Sensor had no connection to a gateway, after ADR_ACK_LIMIT= 64 + ADR_ACK_DEIAY = 32 attempts (EU868)

the Cubecell changing the broadcasting scheme from SF7 to SF8.
Then three packets are received!

SNR 10.8, 10.5, 10.8
RSSI -130, -132, -130,

After that, no more packets are received!

So what happend there? Going back to SF7?

E_T

Update:

After ca. 130 (possible) packets two packets arrived with SF9

SNR -11.8, -13.5

RSSI -132, -134

Update 2

Her the new values: Now we are on SF 11 but the signal performance deteriorates (weather-related?)

Nr Name Date/Time SF SNR RSSI Date/Time
835 mk-cc19-hdc1080 2021-05-23T08:39:31.507900Z 7 -6,5 -126 23.5.21 8:38
836 mk-cc19-hdc1080 2021-05-23T08:39:42.789093Z 7 -6,2 -125 23.5.21 8:38
843 mk-cc19-hdc1080 2021-05-23T08:49:43.612780Z 7 -6,5 -126 23.5.21 8:49
850 mk-cc19-hdc1080 2021-05-23T08:59:44.892476Z 7 -4,5 -124 23.5.21 8:59
874 mk-cc19-hdc1080 2021-05-23T09:39:47.142414Z 7 -9 -129 23.5.21 9:39
886 mk-cc19-hdc1080 2021-05-23T10:09:49.530985Z 7 -6,8 -128 23.5.21 10:09
1281 mk-cc19-hdc1080 2021-05-24T01:30:32.330426Z 8 -10,5 -130 24.5.21 1:29
1312 mk-cc19-hdc1080 2021-05-24T02:30:40.984603Z 8 -12 -132 24.5.21 2:29
1327 mk-cc19-hdc1080 2021-05-24T03:00:45.013562Z 8 -11,5 -132 24.5.21 3:00
1432 mk-cc19-hdc1080 2021-05-24T06:41:12.477539Z 9 -12 -133 24.5.21 6:40
2044 mk-cc19-hdc1080 2021-05-25T01:32:16.505670Z 8 -12 -131 25.5.21 1:31
2158 mk-cc19-hdc1080 2021-05-25T04:31:38.337588Z 9 -12,5 -134 25.5.21 4:31
2176 mk-cc19-hdc1080 2021-05-25T05:01:42.483625Z 9 -12,2 -132 25.5.21 5:01
2852 mk-cc19-hdc1080 2021-05-25T21:12:35.833133Z 8 -10,8 -130 25.5.21 21:12
2862 mk-cc19-hdc1080 2021-05-25T21:22:37.370869Z 8 -10,5 -132 25.5.21 21:22
2872 mk-cc19-hdc1080 2021-05-25T21:32:38.274668Z 8 -10,8 -130 25.5.21 21:32
3708 mk-cc19-hdc1080 2021-05-26T19:04:17.008659Z 9 -11,8 -132 26.5.21 19:03
3715 mk-cc19-hdc1080 2021-05-26T19:14:17.384513Z 9 -13,5 -134 26.5.21 19:13
3819 mk-cc19-hdc1080 2021-05-26T22:04:35.778340Z 9 -13,2 -133 26.5.21 22:03
3842 mk-cc19-hdc1080 2021-05-26T22:34:40.840229Z 9 -13,2 -133 26.5.21 22:34
3880 mk-cc19-hdc1080 2021-05-26T23:34:45.760106Z 9 -13 -131 26.5.21 23:34
3912 mk-cc19-hdc1080 2021-05-27T00:24:51.674120Z 10 -14,2 -134 27.5.21 0:24
3921 mk-cc19-hdc1080 2021-05-27T00:34:53.802190Z 11 -15,8 -135 27.5.21 0:34