This turned out to be faulty/cheap GOVISION cameras. AVOID at all cost!
I literally replaced all cabling and changed balun connections 3/4 times, wasted hours and hours of labour doing this to find out Id been sold cheap cameras under the advert of Hikvision.
Replaced all cameras and all working in night and day! However one camera is condensating from the inside of the lens and customer won’t pay up. I’ve opened camera and made sure all seals are tight and correct still condensating!
I’m fed up of this job now its been a nightmare