PC miner 3.9, started to generate invalid shares

[PSLLSP]

Duino miner 3.9 running at RPI zero

$ python3 -V
Python 3.7.3

MIner was mining for a day, no issue. I noticed today in the web wallet that one miner tries to mine without mining key (I use one!)... I logged to RPI0 console and I see that miner generates invalid shares; it look like an issue at mining pool:

...
10:48:35  cpu0  ⛏ Accepted 1014/1014 (100%) ∙ 15.6s ∙ 240 kH/s ⚙ diff 47 k ∙ ping 20ms
10:48:35  cpu0  ⛏ Accepted 1015/1015 (100%) ∙ 00.2s ∙ 242 kH/s ⚙ diff 11 k ∙ ping 19ms
10:48:48  cpu0  ⛏ Accepted 1016/1016 (100%) ∙ 12.7s ∙ 240 kH/s ⚙ diff 49 k ∙ ping 20ms
10:48:58  cpu0  ⛏ Accepted 1017/1017 (100%) ∙ 10.1s ∙ 240 kH/s ⚙ diff 29 k ∙ ping 20ms
10:49:07  cpu0  ⛏ Accepted 1018/1018 (100%) ∙ 08.8s ∙ 240 kH/s ⚙ diff 25 k ∙ ping 20ms
10:49:38  net0  Error while mining - most likely a connection error - restarting in 5s. timed out
10:49:43  net0  Server message of the day: Welcome to europe node hosted by revox (inst. 1) | NEW: Exchange various cryptocoins fast on fluffyswap.com
10:49:43  net0  Connected to master Duino-Coin server (v3.0, 194.59.183.28)
10:49:59  cpu0  ⛏ Accepted 1/1 (100%) ∙ 08.4s ∙ 226 kH/s ⚙ diff 25 k ∙ ping 7052ms
10:50:08  cpu0  ⛏ Rejected (Incorrect result) 1/2 (50%) ∙ 09.5s ∙ 240 kH/s ⚙ diff 34 k ∙ ping 0ms
10:50:25  cpu0  ⛏ Rejected (Incorrect result) 1/3 (33%) ∙ 17.2s ∙ 240 kH/s ⚙ diff 150 k ∙ ping 0ms
10:50:34  cpu0  ⛏ Rejected (Incorrect result) 1/4 (25%) ∙ 08.6s ∙ 240 kH/s ⚙ diff 150 k ∙ ping 0ms
10:50:47  cpu0  ⛏ Rejected (Incorrect result) 1/5 (20%) ∙ 12.7s ∙ 240 kH/s ⚙ diff 150 k ∙ ping 0ms
10:50:47  sys0  Periodic mining report: 
                ‖ During the last 308 seconds
                ‖ You've mined -991 shares (-3.2 shares/s)
                ‖ Blocks found: 0
                ‖ With the hashrate of 240 kH/s
                ‖ In this time period, you've solved 74040536 hashes
                ‖ Total miner uptime: 25.0 hours
10:51:23  cpu0  ⛏ Rejected (Incorrect result) 1/6 (17%) ∙ 35.9s ∙ 240 kH/s ⚙ diff 150 k ∙ ping 0ms
10:51:42  cpu0  ⛏ Rejected (Incorrect result) 1/7 (14%) ∙ 18.8s ∙ 240 kH/s ⚙ diff 150 k ∙ ping 0ms
10:52:41  cpu0  ⛏ Rejected (Incorrect result) 1/8 (12%) ∙ 59.2s ∙ 240 kH/s ⚙ diff 150 k ∙ ping 0ms
10:53:36  cpu0  ⛏ Rejected (Incorrect result) 1/9 (11%) ∙ 55.0s ∙ 233 kH/s ⚙ diff 150 k ∙ ping 0ms
10:54:31  cpu0  ⛏ Rejected (Incorrect result) 1/10 (10%) ∙ 55.4s ∙ 240 kH/s ⚙ diff 150 k ∙ ping 0ms
10:55:19  cpu0  ⛏ Rejected (Incorrect result) 1/11 (9%) ∙ 48.1s ∙ 240 kH/s ⚙ diff 150 k ∙ ping 0ms
10:55:25  cpu0  ⛏ Rejected (Incorrect result) 1/12 (8%) ∙ 05.1s ∙ 241 kH/s ⚙ diff 150 k ∙ ping 0ms
10:56:11  cpu0  ⛏ Rejected (Incorrect result) 1/13 (8%) ∙ 46.2s ∙ 240 kH/s ⚙ diff 150 k ∙ ping 0ms
10:56:11  sys0  Periodic mining report: 
                ‖ During the last 324 seconds
                ‖ You've mined 0 shares (0.0 shares/s)
                ‖ Blocks found: 0
                ‖ With the hashrate of 240 kH/s
                ‖ In this time period, you've solved 77709946 hashes
                ‖ Total miner uptime: 25.0 hours
10:57:07  cpu0  ⛏ Rejected (Incorrect result) 1/14 (7%) ∙ 55.7s ∙ 231 kH/s ⚙ diff 150 k ∙ ping 0ms
10:58:05  cpu0  ⛏ Rejected (Incorrect result) 1/15 (7%) ∙ 58.5s ∙ 233 kH/s ⚙ diff 150 k ∙ ping 0ms
10:58:16  cpu0  ⛏ Rejected (Incorrect result) 1/16 (6%) ∙ 11.3s ∙ 223 kH/s ⚙ diff 150 k ∙ ping 0ms
...

I just stopped the miner and started it again, it mines, miner configuration was not touched...:

$ cat miner.sh 
#!/bin/sh

[ -f bin/activate ] && . bin/activate

python3 PC_Miner.py "$@"

$ sh miner.sh

 ‖ Official Duino-Coin © Python Miner (3.9) 2019-2023
 ‖ https://github.com/revoxhere/duino-coin
 ‖ CPU: 1x ARMv6-compatible processor rev 7 (v6l)
 ‖ Developer donation level: 0
 ‖ Algorithm: DUCO-S1 ⚙ Low diff
 ‖ Rig identifier: RPI0
 ‖ Config file: Duino-Coin PC Miner 3.9/Settings.cfg
 ‖ Have a wonderful morning, dude!

10:59:17  sys0  Using fasthash hashing accelerations
10:59:18  sys0  Duino-Coin network is a completely free service and will always be
                We don't take any fees from your mining.
                You can really help us maintain the server and low-fee exchanges by donating.
                Visit https://duinocoin.com/donate to learn more about how you can help :)
10:59:23  net0  Searching for the fastest node to connect to
10:59:24  net0  Retrieved mining node: europe-node-1
10:59:24  sys0  Mining thread #0 is starting using DUCO-S1 algorithm with 95% efficiency
10:59:24  net0  Server message of the day: Welcome to europe node hosted by revox (inst. 1) | NEW: Exchange various cryptocoins fast on fluffyswap.com
10:59:24  net0  Connected to master Duino-Coin server (v3.0, 194.59.183.28)
10:59:30  cpu0  ⛏ Accepted 1/1 (100%) ∙ 06.0s ∙ 241 kH/s ⚙ diff 25 k ∙ ping 20ms
10:59:37  cpu0  ⛏ Accepted 2/2 (100%) ∙ 06.4s ∙ 241 kH/s ⚙ diff 35 k ∙ ping 19ms
10:59:47  cpu0  ⛏ Accepted 3/3 (100%) ∙ 10.5s ∙ 240 kH/s ⚙ diff 34 k ∙ ping 19ms
10:59:49  cpu0  ⛏ Accepted 4/4 (100%) ∙ 01.3s ∙ 241 kH/s ⚙ diff 24 k ∙ ping 19ms
10:59:51  cpu0  ⛏ Accepted 5/5 (100%) ∙ 02.2s ∙ 241 kH/s ⚙ diff 47 k ∙ ping 19ms
10:59:59  cpu0  ⛏ Accepted 6/6 (100%) ∙ 08.2s ∙ 241 kH/s ⚙ diff 45 k ∙ ping 19ms
11:00:07  cpu0  ⛏ Accepted 7/7 (100%) ∙ 08.1s ∙ 241 kH/s ⚙ diff 29 k ∙ ping 19ms
11:00:17  cpu0  ⛏ Accepted 8/8 (100%) ∙ 09.8s ∙ 240 kH/s ⚙ diff 30 k ∙ ping 19ms
...

---

Just two hours later and I see the same situation. It looks like miner doesn't have network connectivity (ping 0ms) but it is not true, it is connected. I am connected with ssh client, I can ping internet, so there is no network issue; the issue in in Duino miner. Miner is reconnected from the mining pool, it sends few valid shares and after that all shares are rejected...

...
13:51:25  cpu0  ⛏ Accepted 490/490 (100%) ∙ 05.0s ∙ 240 kH/s ⚙ diff 34 k ∙ ping 19ms
13:51:25  sys0  Periodic mining report: 
                ‖ During the last 300 seconds
                ‖ You've mined 44 shares (0.1 shares/s)
                ‖ Blocks found: 0
                ‖ With the hashrate of 240 kH/s
                ‖ In this time period, you've solved 71869460 hashes
                ‖ Total miner uptime: 2.0 hours
13:51:36  cpu0  ⛏ Accepted 491/491 (100%) ∙ 10.5s ∙ 239 kH/s ⚙ diff 37 k ∙ ping 19ms
13:51:44  cpu0  ⛏ Accepted 492/492 (100%) ∙ 08.1s ∙ 236 kH/s ⚙ diff 33 k ∙ ping 27ms
13:51:44  cpu0  ⛏ Accepted 493/493 (100%) ∙ 00.4s ∙ 228 kH/s ⚙ diff 30 k ∙ ping 19ms
13:51:50  cpu0  ⛏ Accepted 494/494 (100%) ∙ 05.4s ∙ 240 kH/s ⚙ diff 49 k ∙ ping 20ms
13:52:03  cpu0  ⛏ Accepted 495/495 (100%) ∙ 13.6s ∙ 239 kH/s ⚙ diff 37 k ∙ ping 22ms
13:52:12  cpu0  ⛏ Accepted 496/496 (100%) ∙ 09.0s ∙ 239 kH/s ⚙ diff 25 k ∙ ping 20ms
13:52:22  cpu0  ⛏ Accepted 497/497 (100%) ∙ 09.7s ∙ 239 kH/s ⚙ diff 25 k ∙ ping 20ms
13:52:27  cpu0  ⛏ Accepted 498/498 (100%) ∙ 05.2s ∙ 230 kH/s ⚙ diff 25 k ∙ ping 20ms
13:52:30  cpu0  ⛏ Accepted 499/499 (100%) ∙ 02.6s ∙ 240 kH/s ⚙ diff 37 k ∙ ping 19ms
13:52:44  cpu0  ⛏ Accepted 500/500 (100%) ∙ 13.7s ∙ 239 kH/s ⚙ diff 44 k ∙ ping 20ms
13:52:45  cpu0  ⛏ Accepted 501/501 (100%) ∙ 01.5s ∙ 240 kH/s ⚙ diff 16 k ∙ ping 20ms
13:52:52  cpu0  ⛏ Accepted 502/502 (100%) ∙ 06.3s ∙ 239 kH/s ⚙ diff 46 k ∙ ping 20ms
13:52:57  cpu0  ⛏ Accepted 503/503 (100%) ∙ 05.4s ∙ 230 kH/s ⚙ diff 34 k ∙ ping 29ms
13:53:32  net0  Error while mining - most likely a connection error - restarting in 5s. timed out
13:53:37  net0  Server message of the day: Welcome to europe node hosted by revox (inst. 4) | NEW: Exchange various cryptocoins fast on fluffyswap.com
13:53:37  net0  Connected to master Duino-Coin server (v3.0, 85.239.63.53)
13:53:47  cpu0  ⛏ Accepted 1/1 (100%) ∙ 09.2s ∙ 228 kH/s ⚙ diff 25 k ∙ ping 73ms
13:53:48  cpu0  ⛏ Accepted 2/2 (100%) ∙ 01.7s ∙ 230 kH/s ⚙ diff 25 k ∙ ping 39ms
13:53:52  cpu0  ⛏ Accepted 3/3 (100%) ∙ 03.6s ∙ 230 kH/s ⚙ diff 46 k ∙ ping 41ms
13:54:12  cpu0  ⛏ Accepted 4/4 (100%) ∙ 12.1s ∙ 218 kH/s ⚙ diff 41 k ∙ ping 8044ms
13:54:24  cpu0  ⛏ Rejected (Incorrect result) 4/5 (80%) ∙ 11.3s ∙ 238 kH/s ⚙ diff 34 k ∙ ping 0ms
13:54:53  cpu0  ⛏ Rejected (Incorrect result) 4/6 (67%) ∙ 29.4s ∙ 238 kH/s ⚙ diff 150 k ∙ ping 0ms
13:55:36  cpu0  ⛏ Rejected (Incorrect result) 4/7 (57%) ∙ 42.9s ∙ 238 kH/s ⚙ diff 150 k ∙ ping 0ms