I have a hard time believing anyone but an electrical engineer could solder CATx wire and not create an impedance mismatch. Granted 15 Ohms is the tolerance level, but I seriously doubt anyone that posts here could do this in the situation described above with less than 10 Ohms in the mismatch. I'd be surprised if a single poster had the correct tool to even check the impedance in that situation and no it is not a VOM/DMM. You could check the impedance of single wires with a VOM/DMM, but not between two wires. You could even check loop resistance, but again that is not the correct diagnostic for what I am talking about. That said, now we step out of the lab and into the real physical world, it probably works good enough.