Let's Encrypt - Certificate not working

Nov 26, 2017
13
0
1
Finland
cPanel Access Level
Root Administrator
Hi.
i am using Let's Encrypt for my server and for some reason some clients are complaining about non working tls sertificate and https not working on my site.
Any ideas on how to dig further where to find the problem?
Chrome on android said (acording to the customer) : NET::ERR_CERT_AUTHORITY_INVALID