- The runner needs to access `https://[hostname]/api/v3` for downloading actions.
- The runner needs to access `https://[hostname]/_services/vstoken/_apis/.../` for requesting an access token.
- The runner needs to access `https://[hostname]/_services/pipelines/_apis/.../` for receiving workflow jobs.
These can by tested by running the following `curl` commands from your self-hosted runner machine, replacing `[hostname]` with the hostname of your appliance, for instance `github.example.com`:
A common cause of this these connectivity issues is if your to GitHub Enterprise Server appliance is using [the self-signed certificate that is enabled the first time](https://docs.github.com/en/enterprise-server/admin/configuration/configuring-network-settings/configuring-tls) your appliance is started. As self-signed certificates are not trusted by web browsers and Git clients, these clients (including the GitHub Actions runner) will report certificate warnings.
We recommend [upload a certificate signed by a trusted authority](https://docs.github.com/en/enterprise-server/admin/configuration/configuring-network-settings/configuring-tls) to GitHub Enterprise Server, or enabling the built-in ][Let's Encrypt support](https://docs.github.com/en/enterprise-server/admin/configuration/configuring-network-settings/configuring-tls).
- Make HTTP GET to https://vstoken.actions.githubusercontent.com/_apis/health or https://myGHES.com/_services/vstoken/_apis/health using dotnet, check response headers contains `x-vss-e2eid`
- Make HTTP GET to https://pipelines.actions.githubusercontent.com/_apis/health or https://myGHES.com/_services/pipelines/_apis/health using dotnet, check response headers contains `x-vss-e2eid`
- Make HTTP POST to https://pipelines.actions.githubusercontent.com/_apis/health or https://myGHES.com/_services/pipelines/_apis/health using dotnet, check response headers contains `x-vss-e2eid`
If you are seeing `System.Net.Http.HttpRequestException: The SSL connection could not be established, see inner exception.` in the log, it means the runner can't connect to Actions service due to SSL handshake failure.
Contact [GitHub Support](https://support.github.com) if you have further questuons, or log an issue at https://github.com/actions/runner if you think it's a runner issue.