I'll be surprised too if ISP doesn't have any grounding block outside already. It's supposed to be the standard to control additional signal noise.

Something's unusual with his cable choice also. Why does he need to go cat6a on PCs? Regular cat6 will do just fine unless you or your neighboor that is running for ex telecommunication equipment (like ham radio) that might cause an EMI. For regular cable run, cat6 will do just fine. Cat6 for home automation? IoTs like those on smart thermostat, home security system, etc. is way too overkill. Fast internet (100 mbps or less) is more than fine on those. Cat5e is more of a logical choice but still overkill as its rated up to 1 gb.