My operating system is (include version): CentOs 7
My web server is (include version): Apache 2.4.6 (CentOs)
It’s my hosting: IP: 172.126.45.61
I can login to a root shell on my machine (yes or no, or I don’t know): yes
I’m using a control panel to manage my site (no, or provide the name and version of the control panel): no, I use ssh command line and installed letsencrypt through terminal.
No it isn't: in that topic the problem is getting your domain validated, even before issuing a certificate. You already have multiple certificates issued for your domain (see above).