We still use IPv4 a lot and sometimes IPv6 gets in the way.
Soe programs has problem comunicating or it is slow because it tries IPv6 (That is the default) first and than fals back to IPv4
Turning IPv6 off completely is for Windows 2008 and up not a good idea.
You will have some strange things with windows.
But you can change the preference, so prefer IPv4 above IPv6.
This will use IPv4 first.
To do this you have 2 options:
1. A registry change
2. a IPv6 policy change.
I prefer the first but the second option works as well 🙂
Option 1.
Create in the registry on location: HKLM:\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters
a DWORD called: DisabledComponents with value: 20
Option2.
Here the IPv6 addresses are preferred as ::/0 has a precedence of 40, just after the localhost ::1 entry. As you see at any time you can get the current state with netsh interface ipv6 show prefixpolicies.
To have IPv4 favored over IPv6, you must enter a command like netsh interface ipv6 set prefixpolicy ::ffff:0:0/96 46 4 which will make IPv4 addresses have a precedence of 46. By default the entry is made persistent across reboots as opposed to good old route utility under IPv4.