Problems with self signed certificates? (Hostname not verified)

Since v22.0.0 the talk android app requires every HTTPS certificate to list the server’s name in a special field called the Subject Alternative Name (SAN). Older certificates sometimes listed the server name only in another field called the Common Name (CN). That used to work, but modern systems no longer accept it because it can cause security problems and confusion.

If your certificate does not have a Subject Alternative Name, the app will not trust it, even if the name in the CN looks correct.
So if you see the error

Error: Hostname example.com not verified

you’ll need to create or renew your certificate so it includes a Subject Alternative Name that matches your server’s address.

Links with more info on the topic:

https://www.rfc-editor.org/rfc/rfc6125#section-6.4.4
https://groups.google.com/a/chromium.org/g/security-dev/c/IGT2fLJrAeo/m/csf_1Rh1AwAJ
https://stackoverflow.com/questions/5935369/how-do-common-names-cn-and-subject-alternative-names-san-work-together
https://serverfault.com/questions/745560/subject-not-considered-in-a-certificate-with-san

No file, test, or entry point is named. Start by confirming whether the reported CN/SAN behavior is intended and whether this issue should update user-facing guidance; done means a documented resolution or a clearly scoped change.