This is similar to the crashes reported here PMS for Mac (Plex Pass download) crashing on launch after upgrading to 1.14.0.5465
Arises when there is a multi-homed network interface.
Appears to be a Mac OS bug where some info is set incorrectly.
A change has been made to Plex Media Server to get round the crash and will get released in a future version.
In the meantime, getting the output from ifconfig -a in terminal will show which network interface has more than one IP address and may allow you to make a change to avoid the crashes
