Error Renewing SSL

[rsthomas]

The following message appears when trying to run the Let's Encrypt SSL certificate renewal script -- /opt/letsencrypt/letsencrypt-auto renew

------------------------------------------------------------------------
Processing /etc/letsencrypt/renewal/rsthost.com.conf
------------------------------------------------------------------------
Cert is due for renewal, auto-renewing...
Renewing an existing certificate
Performing the following challenges:
tls-sni-01 challenge for rsthost.com
Cleaning up challenges
Attempting to renew cert from /etc/letsencrypt/renewal/rsthost.com.conf produced an unexpected error: Problem binding to port 443: Could not bind to IPv4 or IPv6.. Skipping.
-------------------

This is what is in the above /etc/letsencrypt/renewal/rsthost.com.conf file:
--------------------
# renew_before_expiry = 30 days
version = 0.14.0
archive_dir = /etc/letsencrypt/archive/rsthost.com
cert = /etc/letsencrypt/live/rsthost.com/cert.pem
privkey = /etc/letsencrypt/live/rsthost.com/privkey.pem
chain = /etc/letsencrypt/live/rsthost.com/chain.pem
fullchain = /etc/letsencrypt/live/rsthost.com/fullchain.pem

# Options used in the renewal process
[renewalparams]
authenticator = standalone
installer = None
account = c46d1c485ad1c9a8ccbb0aaddb1384f8
--------------------

This is what is currently in the Sentora Vhost configuration file for the domain in question:
-------------------
# DOMAIN: rsthost.com
<virtualhost *:443>
ServerName rsthost.com
ServerAlias www.rsthost.com
ServerAdmin sales@rstmarine.com
DocumentRoot "/var/sentora/hostdata/rsthost/public_html/"
php_admin_value open_basedir "/var/sentora/hostdata/rsthost/public_html/:/var/sentora/temp/"
php_admin_value suhosin.executor.func.blacklist "passthru, show_source, shell_exec, system, pcntl_exec, popen, pclose, proc_open, proc_nice, proc_terminate, proc_get_status, proc_close, leak, apache_child_terminate, posix_kill, posix_mkfifo, posix_setpgid, posix_setsid, posix_setuid, escapeshellcmd, escapeshellarg, exec"
ErrorLog "/var/sentora/logs/domains/rsthost/rsthost.com-error.log"
CustomLog "/var/sentora/logs/domains/rsthost/rsthost.com-access.log" combined
CustomLog "/var/sentora/logs/domains/rsthost/rsthost.com-bandwidth.log" common
<Directory "/var/sentora/hostdata/rsthost/public_html/">
Options +FollowSymLinks -Indexes
AllowOverride All
Require all granted
</Directory>
AddType application/x-httpd-php .php3 .php
ErrorDocument 500 /_errorpages/500.html
ErrorDocument 510 /_errorpages/510.html
ErrorDocument 404 /_errorpages/404.html
ErrorDocument 403 /_errorpages/403.html
DirectoryIndex index.html index.htm index.php index.asp index.aspx index.jsp index.jspa index.shtml index.shtm
# Custom Global Settings (if any exist)

# Custom VH settings (if any exist)
SSLEngine on^M
SSLProtocol ALL -SSLv2 -SSLv3^M
SSLHonorCipherOrder On^M
SSLCipherSuite ECDH+AESGCMH+AESGCM:ECDH+AES256H+AES256:ECDH+AES128H+AES:ECDH+3DESH+3DES:RSA+AESGCM:RSA+AES:RSA+3DES:!aNULL:!MD5:!DSS^M
SSLCertificateFile /etc/letsencrypt/live/rsthost.com/cert.pem^M
SSLCertificateKeyFile /etc/letsencrypt/live/rsthost.com/privkey.pem^M
SSLCertificateChainFile /etc/letsencrypt/live/rsthost.com/chain.pem^M
# Keeping bellow for future upgrades.^M
# Requires Apache >= 2.4^M
SSLCompression off
</virtualhost>
# END DOMAIN: rsthost.com
##################################################

# DOMAIN: rsthost.com
# PORT FORWARD FROM 80 TO: 443
<virtualhost *:80>
ServerName rsthost.com
ServerAlias www.rsthost.com
ServerAdmin sales@rstmarine.com
RewriteEngine on
ReWriteCond %{SERVER_PORT} !^443$
RewriteRule ^/(.*) https://%{HTTP_HOST}/$1 [NC,R,L]
</virtualhost>
# END DOMAIN: rsthost.com
-------------------

Three different questions:

1.) Have I done something wrong with the above, or have I missed something?

2.) Why do I get a "site not secure" message when using the https://www.rsthost.com/ URL? I have an DNS A Record for www. https://rsthost.com/ works fine.

3.) How do I remove an SSL certificate from a domain?