Encountering an “Unblock request: VPN or proxy detected” or “Anonymous proxy detected” error when accessing banking portals, streaming platforms, enterprise SaaS, or airline booking systems happens even when you are not intentionally running a commercial VPN. Modern Web Application Firewalls (Cloudflare, Akamai, AWS WAF, and MaxMind GeoIP2) combine five distinct network telemetry signals to classify an incoming connection as a proxy. Building on our VPN vs. Proxy Architecture Guide and IP & WebRTC Leak Inspector, this guide explains how proxy-detection engines work and how to resolve false positives step by step.
Interactive “VPN or Proxy Detected” Root-Cause Diagnostic
Select your current connection scenario and operating system to pinpoint why a firewall is flagging your IP or browser—and get the exact fix.
Check three hidden proxy layers that run even when no standalone VPN app is open: (1) Edge “Microsoft Edge Secure Network” or Opera/Brave built-in VPN extensions, (2) Antivirus “Encrypted Web Scanning / VPN” modules (Bitdefender, Avast, Norton), and (3) OS system proxy environment variables (`HTTP_PROXY` / WinHTTP proxy). Run our live IP Inspector to verify your outward-facing ASN.
The 5 Technical Signals Websites Use to Detect VPNs and Proxies
| Detection Layer | What the Server Inspects | Why False Positives Happen |
|---|---|---|
| 1. Autonomous System Number (ASN) Type | BGP ASN classification (`Hosting / Datacenter` vs. `Residential ISP`). | Apple iCloud Private Relay, Cloudflare WARP, and corporate SASE gateways exit from cloud hosting ASNs. |
| 2. TCP/IP Maximum Segment Size (MSS) & MTU | Standard Ethernet TCP MSS is 1460 bytes; WireGuard/OpenVPN encapsulation reduces MSS to 1360–1420 bytes. | PPPoE fiber connections, 5G FWA encapsulations, or custom router MTU settings lower TCP MSS without a VPN. |
| 3. WebRTC STUN ICE Candidate Mismatch | Compares the HTTP request IP against the UDP STUN `srflx` IP returned by the browser’s WebRTC stack. | Browser-only proxy extensions route HTTP through a proxy while UDP WebRTC exits over your real ISP IP. |
| 4. Timezone & Accept-Language Drift | Compares `Intl.DateTimeFormat().resolvedOptions().timeZone` against the GeoIP timezone of the public IP. | Traveling across regions or using privacy browsers that spoof `UTC` timezone while on a local ISP IP. |
| 5. HTTP Proxy Headers (`X-Forwarded-For` / `Via`) | Non-anonymous HTTP proxies append `Via` or `X-Forwarded-For` headers revealing proxy chaining. | ISP transparent caching proxies or enterprise SSL-inspection gateways injecting proxy headers. |
Verify Your Live IP, WebRTC & Proxy Header State in 5 Seconds
Before changing router settings, run our Interactive Public IP, WebRTC Leak & RFC Range Inspector to check whether your connection is exposing a `Via` / `X-Forwarded-For` header or a WebRTC STUN mismatch, and review our VPN vs. Proxy Architecture Comparison.
Written and prepared by Kshitij Gupta.
