The main reason was that the cable runs through a very narrow hole in a thick wall. It would be very hard to open the hole because of the surrounding carpentary and pipework. The current hole just about allows the cable through without the rj-45. There was also a matter of pride. I thought I could handle the connection, and I have done so. I did not appreciate why I might gain from a ready made cable.
There's nothing wrong with using a DIY cable - but you MUST use the correct components i.e. decent cable, decent connectors etc. Clearly your cable is lacking (aluminium core) and we don't know your proficiency in making off RJ45 connections. Even leaving 'too much' of the ends untwisted when making off the plug can have an effect.
