HiHo, As instructed -
there were 5 instances of Blender still active even though Blender was closed - terminated those.
checked the ports and only Blender was using 9001 and 9002 both as IPv4 loopback
Just to be sure I changed the port range on both computers to 11000
Rebooted both computers, restarted blender and checked ports - host machine active ports 11001 and 11002, client machine listening on 1101,2,5,6 and 1107.
Tried test render, which failed, log stated that server didn't have access to the Blender Temp folder, and the client did not have a camera in the scene, which it didn't.
Because the server knew the client did not have a camera I assume they are connected.
Gave the blender temp folder everybody read/write access and addded camera to client blender scene -
(just as an aside - do I have to manually load the Blender project i'm rendering on the client machine ?)
Any way second attempt got 'local render failed' warning on client machine and log file showed lots of authorisation required errors,.-
"2019-12-14 18:16:09,367 ; INFO ; ###################### LOGGING START #######################
2019-12-14 18:16:09,368 ; INFO ; Blender Version ; (2, 81, 16)
2019-12-14 18:16:09,368 ; INFO ; Bl Build type ; b'Release'
2019-12-14 18:16:09,368 ; INFO ; Bl Build Branch ; b'master'
2019-12-14 18:16:09,368 ; INFO ; Bl Platform ; b'Windows'
2019-12-14 18:16:09,368 ; INFO ; Bl bundled python ver ; 3.7.4 (default, Aug 13 2019, 14:10:15) [MSC v.1916 64 bit (AMD64)]
2019-12-14 18:16:09,368 ; INFO ; cr build type ; release
2019-12-14 18:16:09,369 ; INFO ; cr build branch ; trunk/Blender_addon/2.80/User/Crowdrender r1404
2019-12-14 18:16:09,369 ; INFO ; cr system mode is ; 20
2019-12-14 18:16:09,370 ; INFO ; System architecture ; AMD64
2019-12-14 18:16:09,370 ; INFO ; Computer name ; PR001
2019-12-14 18:16:09,370 ; INFO ; Platform details ; Windows-10-10.0.18362
2019-12-14 18:16:09,370 ; INFO ; OS version ; ('10', '10.0.18362', '', '')
2019-12-14 18:16:09,425 ; INFO ; CRClientServerManager.setup_network;Network Interfaces Initialised
2019-12-14 18:16:12,584 ; INFO ; CRFileRequest.__init__:;File Requester connected its inproc channel
2019-12-14 18:16:12,589 ; INFO ; CRClientServerManager.init_session;screen divisions for : local are :()
2019-12-14 18:16:12,589 ; INFO ; CRClientServerManager.init_session;completed sending load_msg
2019-12-14 18:16:13,550 ; WARNING ; CRClientServerManager.handle_disc_httpresp ;Error received from discovery :{'error': 'Authorisation Required'}
2019-12-14 18:20:14,638 ; INFO ; CRClientServerManager.init_session;screen divisions for : local are :()
2019-12-14 18:20:14,639 ; INFO ; CRClientServerManager.init_session;completed sending load_msg
2019-12-14 18:20:15,617 ; WARNING ; CRClientServerManager.handle_disc_httpresp ;Error received from discovery :{'error': 'Authorisation Required'}
2019-12-14 18:20:55,823 ; INFO ; CRClientServerManager.init_session;screen divisions for : local are :()
2019-12-14 18:20:55,823 ; INFO ; CRClientServerManager.init_session;completed sending load_msg
2019-12-14 18:20:56,787 ; WARNING ; CRClientServerManager.handle_disc_httpresp ;Error received from discovery :{'error': 'Authorisation Required'}
2019-12-14 20:15:15,377 ; INFO ; CRClientServerManager.init_session;screen divisions for : local are :()
2019-12-14 20:15:15,378 ; INFO ; CRClientServerManager.init_session;completed sending load_msg
2019-12-14 20:15:16,563 ; WARNING ; CRClientServerManager.handle_disc_httpresp ;Error received from discovery :{'error': 'Authorisation Required'}"
Also, after the failed attempt Blender Server machine had started using multiple random ports - see image.
Intriguing..