Asteriskk 15 spontaneous restsart

Today our server, Asterisk 15.1 spontaneously restarted in the middle of the day, dropping 23 callers.
The logs don’t show anything other than the restart, no error information.
We run a stasis app (hosted on another machine on the LAN) 24/7 for the last couple of months without issue.

https://wiki.asterisk.org/wiki/display/AST/Getting+a+Backtrace