Hi, sorry its taken me a while to write this response. Here is the document that lists the before
values on up/down stream channels (I have tried copying and pasting the values here directly from the router page but the formatting gets all messed up and the router doesn't offer a way to export these values in an usable format and hence the Google drive document, sorry about this!😞
The difference is that upstream power levels have gone down to 40-41dBmV after changing the cable and splitter, before they were at 46-48dBmV. The downstream levels are up to 4-6dBmV from 2-4dBmV
Essentially, the splitter is exactly the same type and number and so is the cable. I can only imagine that the cable might been faulty from day one and it was perhaps only a matter of time before the fault lead to a signal failure/corruption.
Hope this helps someone else experiencing the same problem.