When I got home, websites on my iPhone suddenly started showing certificate warnings saying the connection was not private—even Google and my college's Brightspace site. The problem began after a video stopped playing, although reconnecting initially seemed to help. I tried another browser and saw the same kind of warning there too. Everything works normally when I disconnect from the home Wi‑Fi, and my mom's phone is showing the same errors, so this appears to affect the network rather than a single device. Nobody knowingly changed the router settings. What could cause this, and what should I check?
3 Answers
The warning means the device is receiving a certificate that does not match the website. Before assuming an attack, check that the phone’s date and time are set automatically. If the time is correct and the issue disappears on cellular data but not Wi‑Fi, inspect the router’s DNS and security settings and contact the internet provider if a reboot does not help.
Since multiple phones are affected only while connected to the home Wi‑Fi, this is probably a router or internet-service issue rather than malware on the phones. Restart the router and modem, then check whether the router’s firmware is current. Incorrect DNS settings, a failing router, or an ISP-side problem can cause certificate warnings across many unrelated sites.
A problem with the physical internet connection or recently installed service can also make the router behave strangely, especially if the connection is repeatedly dropping. Check the modem/router status lights and look for outages. Do not bypass the warning or enter passwords on those pages until the network issue is resolved.
That makes sense—the same thing is happening on my mom’s phone, and I’m going to see whether restarting the router clears it up.