This is generally caused by ignorance. Don't understand IPv6 so turn it off without investigating what the actual problem is. Usually it's caused by a broken IP

This is generally caused by ignorance. Don't understand IPv6 so turn it off without investigating what the actual problem is. Usually it's caused by a broken IPv6 configuration - eg a route being announced but no actual connectivity. Here IPv6 works perfectly and doesn't cause any problems. Many sites are much faster over v6 than legacy IP. Google stats show 45% of users access google over IPv6 so clearly it's working for all those millions of users too. If IPv6 is not working you need to fix it, not turn it off.