Measures ping, jitter, download, and upload. All traffic stays on your server.
Note: For upload tests to work correctly, your PHP settings must allow for the configured chunk size.
Make sure upload_max_filesize is at least as large as your chosen chunk size (default 8 MiB),
and post_max_size is large enough to cover all streams combined
(e.g., 8 MiB x 4 streams = 32 MiB).