Crash dumps of these versions are not considered, use the latest version of the server.
Too many changes were made and it will be problematic to disassemble the dump.
In my opinion, there is a RAM leak in version 1.5.6, it does not always occur.
Once I met a leak only on the 16th day of work, and the next time on the 4th day of work.
The increased CPU consumption is caused by a RAM leak in my case.