After receiving the command, the device goes into offline

Hello,
there is a small problem(
After receiving the command, the device goes into offline mode for 10-15 seconds.
Version 3.14 and 3.15, the protocol of the Galileosky. DB mysql. Screen Events table: https://ibb.co/et37K6
Who can help solve it?

You should start by checking server logs.

Anton, you are right, here server log:

2018-01-17 22:45:32  INFO: [8B29B8E8] id: 866050038437777, command type: custom sent
2018-01-17 22:45:32 DEBUG: [8B29B8E8: 5034 > 31.173.99.203] HEX: 011f0003383636303530303338343337353836040000e000000000e105696e616c6caa8a
2018-01-17 22:45:34 DEBUG: [8B29B8E8: 5034 < 31.173.99.203] HEX: 01560003383636303530303338343337353836044701e000000000e13c494e414c4c3a696e303d31313230362c696e313d302c696e323d302c696e333d302c696e343d302c696e353d302c4163633d3536363932343732353bfdef
2018-01-17 22:45:34 DEBUG: [8B29B8E8: 5034 > 31.173.99.203] HEX: 02fdef
2018-01-17 22:45:35  WARN: [8B29B8E8] error - NullPointerException (DeviceManager:214 < OverspeedEventHandler:99 < BaseEventHandler:28 < ...)
2018-01-17 22:45:35  INFO: [8B29B8E8] disconnected
2018-01-17 22:45:44  INFO: [CB507E46] connected
2018-01-17 22:45:45 DEBUG: [CB507E46: 5034 < 31.173.99.203] HEX: 011f80018202100338363630353030333834333735383604470110000020e8a75f5a9de6
2018-01-17 22:45:45 DEBUG: [CB507E46: 5034 > 31.173.99.203] HEX: 029de6

A strange error, what is it?

I understood to mine. Here is the protocol description https://7gis.ru/assets/files/docs/manuals_en/opisanie-protokola-obmena-s-serverom-(487740-v11).pdf

A data block from a device in which the response to the command, does not require confirmation from server.
Here this block:

2018-01-17 22:45:34 DEBUG: [8B29B8E8: 5034 > 31.173.99.203] HEX: 02fdef

Anton, please, help me fix it

That was not the problem, and it's not even response from device. Problem was that command response doesn't include device id or location data. I have fixed the issue.

Thanks! Works great!