Help with HIKVision DS-7608NI-K2/8P camera

[dbrewood]

Okay details:
The NVR is IP address 192.168.1.77
The Drive Camera is 192.168.254.5 (on the NVR network)
The Drive Camera virtual machine port is 65001
The router has a static route sending all traffic for 192.168.254.5 to 192.168.1.77
Ports 554 and 65001-65003 are open on the NAS firewall

Using the Surveillance Station on my Synology NAS (DS918+)I can connect to the camera as (i.e via the NVR and VM port):

So far trying to get FFmpeg working I've tried rtsp parameters of:

rtsp://192.168.1.77:554/Streaming/Channels/101 rtsp://192.168.1.77:554/Streaming/Channels/101/ rtsp://192.168.1.77:65001/Streaming/Channels/101/ rtsp://192.168.254.5:554/Streaming/Channels/101 rtsp://192.168.254.5:554/Streaming/Channels/101/ rtsp://192.168.254.5/Streaming/Channels/101 rtsp://192.168.254.5/Streaming/Channels/101/ rtsp://admin:[password@192.168.1.77](mailto:password@192.168.1.77):554 rtsp://admin:[password@192.168.1.77](mailto:password@192.168.1.77):554/Streaming/Channels/102/ rtsp://admin:[password@192.168.1.77](mailto:password@192.168.1.77)/ISAPI/Streaming/channels/101/HighResolutionVideo rtsp://admin:[password@192.168.1.77](mailto:password@192.168.1.77)/Streaming/Channels/101 rtsp://admin:[password@192.168.254.5](mailto:password@192.168.254.5):554 rtsp://admin:[password@192.168.254.5](mailto:password@192.168.254.5):554/Streaming/Channels/101 rtsp://admin:[password@192.168.254.5](mailto:password@192.168.254.5):554/Streaming/Channels/101/ rtsp://admin:[password@192.168.254.5](mailto:password@192.168.254.5):554/Streaming/Channels/102 rtsp://admin:[password@192.168.254.5](mailto:password@192.168.254.5):554/Streaming/Channels/102/ rtsp://admin:[password@192.168.254.5](mailto:password@192.168.254.5)/ISAPI/Streaming/channels/101/HighResolutionVideo rtsp://admin:[password@192.168.254.5](mailto:password@192.168.254.5)/Streaming/Channels/101 rtsp://admin:[password@192.168.254.5](mailto:password@192.168.254.5)/Streaming/Channels/101/ rtsp://admin:password@http://192.168.1.77:65001/Streaming/Channels/102 rtsp://admin:password@http://192.168.1.77:65001/Streaming/Channels/102/ rtsp://camuser:[password@192.168.1.77](mailto:password@192.168.1.77):554/Streaming/Channels/101/ rtsp://camuser:[password@192.168.1.77](mailto:password@192.168.1.77):65001 rtsp://camuser:[password@192.168.1.77](mailto:password@192.168.1.77):65001/Streaming/Channels/101/ rtsp://camuser:[password@192.168.254.5](mailto:password@192.168.254.5):554/Streaming/Channels/101 rtsp://camuser:[password@192.168.254.5](mailto:password@192.168.254.5):554/Streaming/Channels/101/ rtsp://camuser:password@http://192.168.1.77:65001/Streaming/Channels/101/ rtsp://camuser:password@http://192.168.1.77:65001/Streaming/Channels/102/ rtsp://http://192.168.1.77:65001/Streaming/Channels/101 rtsp://http://192.168.1.77:65001/Streaming/Channels/101/

Which is every combination I can think of - hitting the camera directly or via the NVR with either the RTSP port or the virtual machine port. Typically, I get error:

[Camera FFmpeg] [Drive Cam FFmpeg] FFmpeg exited with code: 1 and signal: null (Error)

Which almost sounds like it's not connecting to the camera. Have I missed the obvious somewhere? Any help would be very much appreciated. This is driving me nuts....