I triedthe latest RealTek drivers first. Didn't solve the problem, but the NEW cable has. Not ONE failure to load the network since I've used it. Old cable when I put it back in did have it working sometimes, but not most of the time.
One thing I didn't check, and probably will later is the ROUTER. New cable used a different RJ45 connection. Possible the one the old cable is in might be loose or problematic. Router has been flashed with private firmware (ASUS RT-N56U with Padavan firmware) and it could be playing into this...
But for now, all is well.