Reason for stopping the server?

Question

Apache HTTP Server

IPhoster's server. ssd-kvm
Ubuntu 16 - 64 bit
all packages are updated
every half a month the server is suspended. the reason, says the caliper, is not on their side.
I look in the logs, I can not find the reason.
syslog at the moment of hangup nothing. cron tasks run successfully and quickly
mysql: 2019-08-04T19:44:07.873685Z 5900 [Note] Aborted connection 5900 to db: 'base' user: 'base' host: 'localhost' (Got an error reading communication packets
but this is not the reason
the only thing found in the Apache logs is an incomprehensible line
who has come across and can help?