Fixes #1465 - add network endpoints (#4920)

Author: sdwheeler

reference/docs-conceptual/gallery/how-to/getting-support/troubleshooting-cmdlets.md

@@ -8,14 +8,26 @@ title:  Troubleshooting cmdlets
 
 ## How to resolve "WARNING: Package 'your package name' failed to download" issue
 
-It is reported that `Install-Module` or `Update-Module` sometimes fails on some machines.
-Based on our investigation, it is something to do with the networking connection.
-Recently we updated NuGet provider so that it can reliably download packages.
-You can follow the instructions below to install the latest build of NuGet provider and then install or update your module.
-Let's use 'Azure' module as an example below.
+It is reported that `Install-Module` or `Update-Module` sometimes fails on some machines. Based on
+our investigation, it is something to do with the networking connection. Recently we updated NuGet
+provider so that it can reliably download packages. You can follow the instructions below to install
+the latest build of NuGet provider and then install or update your module. Let's use 'Azure' module
+as an example below.
 
 ```powershell
 Install-PackageProvider NuGet -MinimumVersion 2.8.5.206 -Force
 Launch new PowerShell Console
 Update-Module Azure -Verbose
 ```
+
+### Required network endpoints
+
+The Install and Update cmdlets require internet access to connect to the network endpoints used by
+by the PowerShell Gallery. Ensure that your network access policies allow you to connect to the
+following endpoints.
+
+- oneget.org
+- go.microsoft.com
+- az818661.vo.msecnd.net
+- www.powershellgallery.com
+- devopsgallerystorage.blob.core.windows.net