Suddenly we started receiving the next errors:
Error Code: 2013 Lost connection to MySQL server at 'reading initial communication packet', system error: 0
Error Code: 2003 Can't connect to MySQL server on '188.8.131.52' (10061)
After checking the log we found out that MariaDB is not able to restart after some fatal crash. Please investigate the log, I've attached the whole day trace, you may find a crash starting at about 12:55.