Recently, Google frequently shows an "Our systems have detected unusual traffic" message and asks me to complete a CAPTCHA before searching. I don't use a VPN myself, but my partner does and we share the same Wi‑Fi. Could their VPN be causing this? I've also searched some unusual questions about laws and cannabis while traveling, so I'm wondering whether the search terms themselves could be contributing.
2 Answers
Your partner’s VPN is a likely cause, especially if it’s a cheap or free service. Some free VPNs route traffic through users’ connections, and shared VPN exit addresses can generate a lot of suspicious activity. Google may flag the entire address when many people are using it or when someone on that address is making automated requests. A reputable paid VPN is generally safer, although even legitimate VPNs can occasionally trigger CAPTCHAs.
There are several possible explanations. If your internet provider uses CG-NAT, your public IP address may be shared by many customers, so another person’s heavy or suspicious traffic can cause Google to challenge everyone using that address. If you have a dedicated public IP, repeated searches, automated software, malware, or a VPN on your network could be responsible. Unusual search wording alone usually isn’t enough, but a high volume of searches or activity that resembles automation can trigger the warning.

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