The server freezes - the memory is running out - did you review everything?

Question

linux

I reboot Apache, there is memory. After some time, it equals 0.
Buffer 0k is always
On the server 2 gigabytes of memory, there is a Bitrix virtual machine with a small business edition, 300 visitors per day.
It used to work fine - a month or two without rebooting. Now it hangs 5 ​​times a day, so it's impossible to reach ssh. And okay, it hung and went into a reboot, so no - you have to get up at night to reboot on a call.
Configs checked everything, logs too.
In the logs, he swore at maxclients. So I turned it off and it didn't help.
The server is crashing apparently due to a memory leak.
But there is nothing more intelligible in the logs.
in configs
Timeout 60
KeepAlive On
MaxKeepAliveRequests 100
KeepAliveTimeout 5

StartServers 1
MaxClients 7
MinSpareThreads 25
MaxSpareThreads 75
ThreadsPerChild 25
MaxRequestsPerChild 128

The only thing is that we updated to version 17 of Bitrix. But I doubt that's the issue.
If you need some more configs, then I'm ready to lay out.
I noticed that the memory does not disappear instantly.
I launch TOP and look. Then at some point it's 0.