There are several situations in which the browser does not trust SSL certificates:
1, self-signed SSL certificate.
2. SSL certificates of all browsers are not supported.
3. Expired SSL certificate
4. There are unsafe factors in the 4.https page.
5, sha 1 algorithm, and issue a certificate to 20 17.
6. The untrusted certificate specified by the browser.
In your case, UC and the browser that comes with your mobile phone don't trust the certificate. You should test it with Google browser. In addition, see if the time on the mobile phone is synchronized with the network. I use the free SSL certificate of wosign, which can be displayed perfectly on both mobile phones and PCs. I hope I can help you.