Also, when you say that you are creating a jail, you really mean that you are installing a plugin, in this case, Plex?
What about if you just try to create a standard jail? What happens.
Additionally, you have a ton of RAM and a lot of CPU power, if you haven't already done so you really need to test them out. I'd run MemTest86 for a week on all that RAM and a CPU stress test for maybe 20 minutes. You should also run a stress test on your hard drives/controller card by doing some lengthy "dd" data transfers (or similar) just to see how it holds up to constant use.
As for the NIC, do you have LAGG configured in the VM? If you do then you should just simplify it, even on bare metal, get rid of the LAGG and see how it works.