I posted this in the Apple Support Communities forum, but haven't gotten any replies, so here it goes:
I have a 2012 Mac Mini i7 running 10.11.1 and OS X Server 5.0.15. Among other things, I use the Mini as a Plex Media Server for streaming within my LAN as well as over the internet to my iOS devices. All of this worked fine when I was running OS X Server 4.x, whether I set up manual port forwarding rules or allowed Plex to open ports via NAT-PMP (I have an AirPort Extreme router). However, following the update, I am no longer able to access my media library over WAN (LAN works fine, including when I VPN into my home network). I can provide additional details, but essentially an inability to forward to the internal TCP port on the server (TCP 32400), whether manually or via NAT-PMP, seems to be the issue. Might this have something to do with the reverse proxy issue that others have commented upon relating to OS X Server 5?
Other information that might be relevant:
My cable modem has a static IP, as does the Mac Mini Server
MTU is 1500
I do not have double NAT
My ISP does not block port 32400
OS X Server services for which port forwarding is working fine are: VPN (L2TP), Profile Manager, Websites, Wiki
canyouseeme indicates that port 32400 is closed, even if I manually forward the port to my Server using AirPort Utility
I have tried redirecting outside TCP port 36251 (an arbitrary one) to internal TCP 32400 at my server's static IP - doesn't fix it
Any ideas??