RPi3 Switch Off IPV6

Step

1. Add these lines to /etc/sysctl.conf :

   net.ipv6.conf.all.disable_ipv6 = 1
   net.ipv6.conf.default.disable_ipv6 = 1
   net.ipv6.conf.lo.disable_ipv6 = 1
   net.ipv6.conf.eth0.disable_ipv6 = 1
   net.ipv6.conf.[interface].disable_ipv6 = 1

2. Use sudo sysctl -p to apply changes

3. Reboot