Nope, that didn't fix the DHCP issue and, in fact, it shouldn't be the logical configuration, as FN should go to my DHCP Server to get a free IP, not provide an IP from a range you'd specify in it. That could cause IP conflicts inside the network.
I'm super new to this, so bare with me. But I'm not specifying any IP address ranges anywhere in FreeNAS. I thought the DHCP option in the Jails -> Configuration meant "I'm using a DHCP server use IT to get an IP address, don't try to create IPs on the server (freeNAS jails)". Again, on my FreeNAS Jails -> configuration I have DHCP enabled, if I click advanced options the 'range' is grayed out. (adding screenshot)
Which leads me to believe that FreeNAS will not try to 'create' IPs, instead it'll use the DHCP on my router (which is also my default gateway). Then inside the jail itself for PLEX, I also have DHCP enabled, which I believe requests an ip from the "jails manager" (if I can call it that).
So to recap, this is how I understand it.
The Plex jail == DHCP enabled, which then it goes to it's parent the 'all jails' config, in my case, also DHCP, which then goes to the network and says 'gimmie an ip'.
Anyways, I'm sorry that didn't fix your issue, hopefully someone that actually understands this stuff will chime in (meaning not me).