Find the problem
“Certificate not trusted” on iPhone?
The warning means one precise thing: your phone could not verify the identity behind an encrypted connection. It has a handful of causes, they look identical in the browser, and they are easy to tell apart.
1. One site, or every site?
This single question does most of the work.
- Every site, right after joining hotel, cafe or airport Wi-Fi: that is a captive portal. The network answers every request with its own login page until you sign in, and the warning is your phone catching the interception - the protection is working. Sign in to the network's own page first; the warnings end when the network stops intercepting.
- Every site, on every network, even cellular: check your phone's date and time in Settings. A wrong clock breaks every certificate on earth at once, because validity is a date range.
- One site: continue.
2. Ask for the real reason
Open TLS Inspector and enter the site's name. It reads the certificate straight from your device and names the cause instead of a vague warning:
- Expired: the dates row shows the certificate lapsed. That is the site's side; nothing on your phone is wrong.
- Hostname mismatch: the certificate belongs to a different name. Check the exact address you typed: look-alike domains and odd subdomains live here.
- Self-signed or untrusted chain: the site presents an identity no public authority vouches for. On your own router's settings page this is expected (see Can't open your router's settings page); on a public website it is a real warning.
What you now know
The warning has a named cause: the network intercepting, your clock, their expired paperwork, a wrong address, or a private identity. The one thing not to do is tap through a warning you have not explained - on your own router it is expected; anywhere else, the warning is doing its job.
Every check on this page runs free in Radien, entirely on your iPhone.
