Deep Packet Inspection: Is Your ISP Throttling Netflix?

ISPs use hardware appliances to perform Deep Packet Inspection (DPI). They look at the SNI in your TLS handshake to identify "netflix.com" and artificially limit the bandwidth.

1. The "Fast.com" vs "Speedtest.net" Test

Netflix created Fast.com specifically to expose this.

The Test: Run a test on Speedtest.net, then immediately on Fast.com. If Speedtest shows 100Mbps and Fast.com shows 5Mbps, your ISP is throttling video traffic.

2. The VPN Control

Turn on a VPN (like WireGuard). This encrypts the SNI. Run the video test again. If the speed restores, you have definitive proof of traffic shaping.