Why does Android swear at the certificate?

Question

Android

Greetings. I made a PositiveSSL Wildcard Certificate for a Comodo domain. Received 2 files from them:
1) STAR_site_ru.ca-bundle
2) STAR_site_ru.crt
Made PEM:

cat STAR_site_ru.crt STAR_site_ru.ca-bundle > cert.pem

Installed on nginx. There are no problems on the desktop versions of all browsers, the certificate is trusted. If you go from chrome to Android, it swears that Certificate is not trusted. "The server certificate is not trusted."
What is the problem?

Answer 1

In general, the cant was on my side in setting up Nginx. Domain certificate + ca-bundle file created a working chain. Thanks to all.

Answer 2

See if there is one in the root certificate store that signed the one issued to you. Have you tried from different devices? Try to put FF for android and go from there.

Answer 3

Maybe the time is wrong on the device?

Answer 4

I recently encountered the fact that the certificate chain provided by Comodo was not trusted in ios. Found another chain for my cert that worked for all devices.