Weird issue with a device using h02 protocol

I have 2 different Chinese devices that use the same protocol, h02 (TQ as the manufacturer name it) port:5013. One is working normally but the other one shows permanently offline but counts the offline time like it was online.

I have connected the not-working device to another server that uses another system similar to GPS SERVER and connected it to the same port of the TQ/h02 protocol, and it did work just fine.

One more notice is that when I connect that device to the server on port 5013 its green light starts flashing like it cannot connect to the server. Switched it to the other ports like 5023 or 5004, the green light got fixed like it has been connected to the server but the Traccar still cannot display the device location. The same thing happens when connected to the other non-Traccar server, the green light gets fixed.

Does anyone have any clue what's going on?

Have you checked logs?

Here's the log file:
https://drive.google.com/file/d/1A_Ock2SP8h06MqSLv1iBKaAoZOf58FuI/view?usp=sharing

The ID of the device is 8019237050.

I only can see the device when connected to the gt06 and gl200 protocols, but there's no trace of it at the protocol h02, like the server block the device at the 5013 port.

You need to figure out the port 5013 problem. Traccar doesn't block any connections, so the issue is somewhere else.

That's why I called it weird, because other devices are connected to the 5013 port without any issues!

Traccar is hosted on a Ubuntu at Digital Ocean, any clue what can block connection to the 5013 port?

I restarted the server, and I have even changed the protocol's port to another one and got the same issue. Some devices are connected fine and others are unable to connect to that protocol's port.

I have managed to recognize the log of the device without the ID, and here they are:

2021-01-18 13:27:02  INFO: [5a353eeb] connected
2021-01-18 13:27:02  INFO: [5a353eeb: h02 < 105.67.6.199] HEX: 2a48512c383031393233373035302c56312c3133323730312c412c333330362e373530332c4e2c30303735362e323632392c572c3030312e33302c3332342c3138303132312c46464646464246462c3630342c30322c3231302c323637323223
2021-01-18 13:27:02  INFO: [5a353eeb: h02 > 105.67.6.199] HEX: 2a48512c383031393233373035302c56342c56312c323032313031313831333237303223
2021-01-18 13:27:02  WARN: [5a353eeb] error - NullPointerException (DeviceManager:430 < *:419 < OverspeedEventHandler:123 < BaseEventHandler:29 < ...)
2021-01-18 13:27:02  INFO: [5a353eeb] disconnected
2021-01-18 13:27:06  INFO: [fd301835] connected
2021-01-18 13:27:06  INFO: [fd301835: h02 < 105.71.144.17] HEX: 2a48512c383031393233373035302c56312c3133323730352c412c333330362e373530382c4e2c30303735362e323633382c572c3030322e30332c3332392c3138303132312c46464646464246462c3630342c30322c3231302c323637323223
2021-01-18 13:27:06  INFO: [fd301835: h02 > 105.71.144.17] HEX: 2a48512c383031393233373035302c56342c56312c323032313031313831333237303623
2021-01-18 13:27:06  WARN: [fd301835] error - NullPointerException (DeviceManager:430 < *:419 < OverspeedEventHandler:123 < BaseEventHandler:29 < ...)
2021-01-18 13:27:06  INFO: [fd301835] disconnected

Is it a protocol issue or what?

You should check the source code line from the stack trace and see what causes it.