Hello Dan, pleased to meet you and thanks for the prompt reply.
I just need to get a picture in my head of the connection plan.
So I dont use the cable that goes from outside the front door to the loft, or if I do, the switch or injector will be in the loft, but need to connect to my router...
I have a Hikvision DS-7608NI-I2-8P in the loft, power in the loft.
I also have 3 x DS-2CD2347G2-LSU/SL.
When it was installed I had a CAT5 cable run down to the front door if I was going to add another camera facing out from the above the front door.
I would like, or thought I did, a doorbell...