@chopstix You solved my issue - Many Thanks.

2 x 8 port NVR's on the same home network - one in the house and one in the shed ; each with their own POE switch and 4 cameras

Had been working for a long time and I upgraded teh firmware on the NVR's BOTH at teh same time - BAD BOY. I could get random Camera's to appear on either NVR but not the same - I could see all cameras but never connect - all sorts of User /Password warnings and one that said Abnormal Config - connecting to a new NVR.

I spent HRS trying all sorts of full resets and network configs. Was ready to toss the lot in the bin

Unit one - went and added a password to the cameras I had a connection - then did the same on Unit 2. Was then able to add all eight camera's to each NVR.

Now to finish settings and configure mail and notifications.

Doorbell Poe