Letsencrypt New domain ssl issued not trust problem

First try running your intended SSL certificate domain through the letsdebug.net online testing tool to check for potential errors with HTTP-01 validation. If you created Centmin Mod 123.09beta01 or higher Nginx site with Letsencrypt via centmin.sh menu option 2, 22 or nv command line, you now also have an automatic letsdebug.net API check log saved at /root/centminlogs/letsdebug-yourdomain.com-${DT}.log where yourdomain.com is domain specified during nginx vhost creation and DT is date/timestamp. Inspecting the /root/centminlogs/letsdebug-yourdomain.com-${DT}.log log will also give you clues as to why letsencrypt SSL certificate issuance failed.

Centmin Mod Self-Signed SSL Fallback

If you're seeing a Centmin Mod's self-signed untrusted ssl certificate instead of letsencrypt ssl certificate, then that's acmetool.sh and centminmod's fallback if letsencrypt verification fails to obtain letsencrypt ssl cert, it falls back to centmin mod self-signed ssl certificate on https port 443 side so to preserve the https nginx vhost

Troubleshooting

There are various steps you can do to troubleshoot failed letsencrypt issuances, renews, reissues etc.

• acmetool.sh logs all command line or shell menu runs to log files at /root/centminlogs. To troubleshoot, copy the contents of the log run and post contents of log to pastebin.com or gist.github.com and share link in this thread. To find the log list the logs in ascending date order
  Code (Text):

  ls -lahrt /root/centminlogs

  .
• For direct acmetool.sh runs, there should be a 2nd & 3rd & 4th log in format /root/centminlogs/centminmod_${DT}_nginx_addvhost_nv.log and /root/centminlogs/acmetool.sh-debug-log-$DT.log and /root/centminlogs/acmesh-issue_*.log or /root/centminlogs/acmesh-reissue_*.log which would need to be included via separate pastebin.com or gist.github.com post.
• Enable acmetool.sh debug mode. In persistent config file at /etc/centminmod/custom_config.inc (create it if doesn't exist) add and enable acmetool.sh debug mode which gives much more verbose letsencrypt issuance process information when you re-run acmetool.sh or centmin.sh menu options 2, 22 or /usr/bin/nv command lines.
  
  Code (Text):

  ACMEDEBUG='y'

If acme.sh auto renewals didn't happen, check output for the following commands

Code (Text):

grep acme /var/log/cron* | sed -e "s|$(hostname -s)|host|g"

Code (Text):

echo y | /usr/local/src/centminmod/addons/acmetool.sh checkdates

Code (Text):

"/root/.acme.sh"/acme.sh --cron --home "/root/.acme.sh"

Code (Text):

echo | openssl s_client -connect yourdomain.com:443

Without the answers to above questions and logs, there is nothing to help troubleshoot.

SSLLabs Test

Also run your HTTPS domain site through SSLLabs tester at SSL Server Test (Powered by Qualys SSL Labs) if it says untrusted SSL cert and prompts to continue the test, continue the test.