All the command that I use for Let's encrypt
sudo add-apt-repository ppa:certbot/certbot
sudo apt install python-certbot-nginx
Process Certbot Domain
Check all certificate
sudo certbot certificates
Adding subdomain from existing certificate
sudo certbot delete --cert-name example.com
- Try to make folder .well-known/acme-challenge/test.html and run it to browser if works try again.
- Try to stop nginx and start it again... not reload but to stop first and start again.
Worth to look