Restore Application Update and API Connectivity
Skyhigh Client (SC) 5.x may block applications from downloading updates or accessing API endpoints. This issue commonly appears after upgrading from SCP 4.9.x, where the same applications worked as expected.
SC 5.x interprets IPv4-mapped IPv6 connections as IPv6 traffic and applies IPv6 block policies. Even though the application targets an IPv4 destination, the operating system presents the connection in IPv6 format. SC then enforces a Global IPv6 block and prevents the connection. As a result, the application fails to establish outbound connections to update servers or API URLs.
Impact
Applications fail to download updates or access API endpoints when they attempt outbound connections through SC 5.x.
SC logs show that the proxy identifies the traffic as IPv6 and applies a Global IPv6 block. In the Debug.log file, the destination IP appears as 0.0.0.0, while the protocol is marked as 6 and the IP version as 6.
Even if you disable IPv6 on the network adapter or DNS server, the behavior continues because the operating system still presents the connection in IPv6 format.
Resolution
Configure the system to prevent applications from using IPv4-mapped IPv6 addresses.
Set the following environment variable:
- Variable Name.
DOTNET_SYSTEM_NET_DISABLEIPV6 - Value.
1
This configuration forces supported applications to use the IPv4 stack and prevents SC from identifying the traffic as IPv6.
You can apply this configuration using one of the following methods, depending on your environment and deployment requirements.
Configuration
Select the method based on your environment:
- Use the Windows GUI for manual configuration on individual systems.
- Use the Command Line to configure the registry directly.
- Use Group Policy to deploy the setting across multiple systems in an enterprise environment.
Configure Using Windows GUI
- Click Start.
- Search for Edit the system environment variables.
- Open the result with Administrator privileges.
- Click Environment Variables.
- Under System variables, click New.
- Enter:
- Variable name.
DOTNET_SYSTEM_NET_DISABLEIPV6 - Variable value.
1
- Variable name.
- Click OK.
- Restart the system.
Configure Using Command Line
Open Command Prompt as Administrator.
- Set for the Entire System.
reg add "HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" /v DOTNET_SYSTEM_NET_DISABLEIPV6 /t REG_SZ /d 1 /f - Set for Current User Only.
reg add "HKCU\Environment" /v DOTNET_SYSTEM_NET_DISABLEIPV6 /t REG_SZ /d 1 /f
Restart the system after applying the configuration.
Deploy Using Group Policy
- Open the Group Policy Management Console (GPMC).
- Go to Computer Configuration > Preferences > Windows Settings > Environment
- Select New > Environment Variable.
- Configure:
- Action. Update
- Variable type. System Variable
- Name.
DOTNET_SYSTEM_NET_DISABLEIPV6 - Value.
1
- Apply the policy.
- Restart the system after applying the policy.
Verify the Configuration
Open PowerShell and run Get-ChildItem Env:DOTNET_SYSTEM_NET_DISABLEIPV6
If the configuration is correct, the system displays DOTNET_SYSTEM_NET_DISABLEIPV6 : 1