How to disable IPv6

How to Disable IPv6 (Internet Protocol version 6)

You can disable IPv6 on the host computer through the DisabledComponents registry value. The DisabledComponents registry value affects all network interfaces on the host.

Important: Follow the steps below carefully. Serious problems might occur if you modify the registry incorrectly. Before you modify it, back up the registry for restoration in case problems occur.

To disable certain IPv6 components, follow these steps:

Step 1: Click Start, type in "regedit" in the Start Search box, and then click regedit.exe in the Programs list.
Step 2: If you see a User Account Control dialog box, click Continue
Step 3: In the Registry Editor, locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Services \ Tcpip6 \ Parameters \
Step 4: Double-click DisabledComponents to change the DisabledComponents entry.

Note: If the DisabledComponents entry is unavailable, you must create it. To do this, follow these steps:
     a. In the Edit menu, point to New, and then click DWORD (32-bit) Value.
     b. Type DisabledComponents, and then press Enter.
     c. Double-click DisabledComponents.

Step 5: Type 0xff in the Value data field, and then click OK. (This will configure the IPv6 protocol to the intended state, which is to disable all IPv6 components except the IPv6 loopback interface. This value also configures Windows to prefer using IPv4 over IPv6 by changing entries in the prefix policy table).

Use the DisabledComponent registry value to verify whether IPv6 is disabled. To do this, run the following command at a Windows command prompt:

reg query HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters /v DisabledComponents

When you do this, you may receive the following error message: 
" ERROR: The system was unable to find the specified registry key or value."

If you receive this error message, the DisabledComponents registry value is not set. If the DisabledComponent value is set, it overrides the settings in the connection properties.

 

For additional information regarding disabling IPv6, see this link:
https://support.microsoft.com/en-us/kb/929852