I know this may sound simple but have you are trying the SL ports not the LS.
Just to be safe have you put your test butt across all the RJ11's on the back.
Hi Sarond, It's always the simplest questions that are never asked. Guess what! It's the correct question to ask!! The engineers put the cables in the LS ports instead of the ONS ports. I've moved them across and they are all working now.
Many thanks to you and everyone else who contributed to this. Thank you all!!!1