PS4 Indirect connection solved:
Thanks for the leads in this thread Guys n Girls
- I have Just set up a New PS4
- On the same network as my server
- Conected wirelesly
- BT Smart Hub 7 (Manual DNS config not allowed)
- Windows 10 PLEX server
Fix for Indirect connection, slow startup, menu / app hang and disconection / Dropping while Playing.
- Configured Google DNS in Windows 10 [How to change DNS settings on your PC running Windows 10 | Windows Central]
- Set PLEX server - Settings - Network - Secure connections [Disabled]
- Set PLEX server - Settings - Remote Access - Manually specify public port - [32400] - Apply
- BT HUB - Checked Port forwarding exists for PLEX 32400
- BT HUB - PS4 should have created port rules automatically
- Restarted PC and PS4
- PLEX PS4 - [User dropdown] - Settings - Main - Alow fallback to Insecure connections [ON]
- PLEX PS4 - [User dropdown] - Settings - Manual Servers - Visually confirmed Connection 1& 2 Port = 32400 (connection numbers may vary)
- Restarted PC and PS4 for good measure.
I tried many other variations and checks including dedicated VPN Streaming IP but this concise list is simple and reproducable for the hardware setup configuration mentioned. So far Zero issues. 
Hope this helps some one
Bush Baby, Last survivor of the Nostromo, Signing off.