Networking TSG (#1325)

* Update Network Troubleshooting doc

* fix list

* Update network.md

docs/checks/network.md

@@ -2,17 +2,19 @@
 
 ### Common things that can cause the runner to not working properly
 
-- Bug in the runner or the dotnet framework that causes actions runner can't make Http request in a certain network environment.
+- A bug in the runner or the dotnet framework that causes the actions runner to be unable to make Http requests in a certain network environment.
 
-- Proxy/Firewall block certain HTTP method, like it block all POST and PUT calls which the runner will use to upload logs.
+- A Proxy or Firewall may block certain HTTP method, such as blocking all POST and PUT calls which the runner will use to upload logs.
 
-- Proxy/Firewall only allows requests with certain user-agent to pass through and the actions runner user-agent is not in the allow list.
+- A Proxy or Firewall may only allows requests with certain user-agent to pass through and the actions runner user-agent is not in the allow list.
 
-- Proxy try to decrypt and exam HTTPS traffic for security purpose but cause the actions-runner to fail to finish SSL handshake due to the lack of trusting proxy's CA.
+- A Proxy try to decrypt and exam HTTPS traffic for security purpose but cause the actions-runner to fail to finish SSL handshake due to the lack of trusting proxy's CA.
 
-- Proxy try to modify the HTTPS request (like add or change some http headers) and causes the request become incompatible with the Actions Service (ASP.NetCore), Ex: [Nginx](https://github.com/dotnet/aspnetcore/issues/17081)
+- The SSL handshake may fail if the client and server do not support the same TLS version, or the same cipher suites.
 
-- Firewall rules that block action runner from accessing certain hosts, ex: `*.github.com`, `*.actions.githubusercontent.com`, etc.
+- A Proxy may try to modify the HTTPS request (like add or change some http headers) and causes the request become incompatible with the Actions Service (ASP.NetCore), Ex: [Nginx](https://github.com/dotnet/aspnetcore/issues/17081)
+
+- Firewall rules that block action runner from accessing certain hosts, ex: `*.github.com`, `*.actions.githubusercontent.com`, etc
 
 
 ### Identify and solve these problems
@@ -29,4 +31,31 @@ Use a 3rd party tool to make the same requests as the runner did would be a good
 
 If the 3rd party tool is also experiencing the same error as the runner does, then you might want to contact your network administrator for help.
 
-Otherwise, contact GitHub customer support or log an issue at https://github.com/actions/runner
+Otherwise, contact GitHub customer support or log an issue at https://github.com/actions/runner
+
+### Troubleshooting: Why can't I configure a runner?
+
+If you are having trouble connecting, try these steps:
+
+1. Validate you can reach our endpoints from your web browser. If not, double check your local network connection
+    - For hosted Github:
+      - https://api.github.com/
+      - https://vstoken.actions.githubusercontent.com/_apis/health
+      - https://pipelines.actions.githubusercontent.com/_apis/health
+    - For GHES/GHAE
+      - https://myGHES.com/_services/vstoken/_apis/health
+      - https://myGHES.com/_services/pipelines/_apis/health
+      - https://myGHES.com/api/v3
+2. Validate you can reach those endpoints in powershell core
+    - The runner runs on .net core, lets validate the local settings for that stack
+    - Open up `pwsh`
+    - Run the command using the urls above `Invoke-WebRequest {url}`
+3. If not, get a packet trace using a tool like wireshark and start looking at the TLS handshake. 
+    - If you see a Client Hello followed by a Server RST:
+      - You may need to configure your TLS settings to use the correct version
+        - You should support TLS version 1.2 or later
+      - You may need to configure your TLS settings to have up to date cipher suites, this may be solved by system updates and patches.
+      - Your firewall, proxy or network configuration may be blocking the connection
+      - You will want to reach out to whoever is in charge of your network with these pcap files to further troubleshoot
+    - If you see a failure later in the handshake:
+      - Try the fix in the [SSLCert Fix](./sslcert.md)