Internet is crawling (single-digit Mbps or less) and the user blames "the Wi-Fi", but the Wi-Fi link is measurably healthy: strong RSSI, high negotiated PHY rate, and a 2-3ms ping to the default gateway with zero loss. No local process is consuming bandwidth. Standard Wi-Fi troubleshooting (channel changes, band switching, moving closer to the AP) is wasted effort because the bottleneck is entirely on the WAN side. The failure looks like a LAN problem to the user because that is the only part of the path they can see.

Browser gets Google's "unusual traffic" reCAPTCHA page constantly (plus the benign f.txt download side effect) even though the browser config looks fine. Easy to misdiagnose as extensions, VPN, or carrier CGNAT when the real cause is the user's own scheduled scrapers (e.g. Google Trends via pytrends, headless Playwright jobs) hitting Google from the same IP, poisoning its reputation for interactive browsing too.