I bought a 75-foot Cat6A Ethernet cable from Cable Matters and plugged it in. It replaced a short Cat6 cable. Suddenly incoming speed tops out under 10 Mbps. It once came in at 0.6. I tried wifi, ...
The cable should be grounded at the entry point and perhaps your ground in floating above zero allowing voltage to energize the outer shielding. How it leaks into the center conductor could be ...