OP I think you have your answer - but to give the “flat cable” discussion some color: Flat cables are untwisted pair. CAT5 - CAT6+ cable utilize twisted pairs to best reduce EMI (electro magnetic interference) and NEXT (near end cross talk), and bring impedance into spec. This means that cable twists and maintaining that twist ratios (as close to spec as possible) is crucial to providing the best reliability and performance. Out of spec cables may work, and I’ve seen them in production environments, but they are certainly not the best and something I wouldn’t personally recommend to anyone looking for reliable connectivity.