Is the SSL certificate on the PC all right, does it not trust on the smartphone?

Question

Google Chrome

I log in the same domain from a PC through chrome

The same address, through a smartphone on an android chrome application

Answer 1

Combined 3 certificates into one *.crt
1. Intermediate certificate
2. Root certificate
3. personal
By the way, SSL certificates are free for a year, when buying a domain www.reg.ru/domain/new/?rid=79193

Answer 2

It was the same. HZ with what is connected ...

Answer 3

My Let'sEncrypt certificate is blocked on Firefox and mobile browsers, FF says the reason is an unknown registrar (Let'sEncrypt is a fairly new registrar)

Answer 4

Well, the first thing that comes to mind is that on the PC the publisher of the certificate is in trusted root, but not on smart.