When your website goes down, quick diagnosis is essential. This guide provides a systematic approach to identifying and fixing the most common causes of website downtime on your Data Mammoth server.

Quick Diagnosis Flowchart

Work through these checks in order — each step narrows down the cause:

Step 1 — Check Server Status

Also check for any billing-related suspensions — overdue invoices can cause service suspension. See How to Pay an Invoice.

Step 2 — Test SSH Access

ssh [email protected]

• If SSH connects — The server is online. Proceed to check web services.
• If SSH times out — The server may be unresponsive or the firewall may be blocking SSH. Try the web console.
• If SSH is refused — SSH service may be down. Use the web console.

Step 3 — Check the Web Server

Nginx

sudo systemctl status nginx

If Nginx is not running:

sudo systemctl start nginx

If it fails to start, check the configuration:

sudo nginx -t

Fix any errors reported, then restart.

Apache

sudo systemctl status apache2    # Ubuntu/Debian
sudo systemctl status httpd      # CentOS/AlmaLinux

If not running:

sudo systemctl start apache2

Check configuration:

sudo apache2ctl configtest

Step 4 — Check Error Logs

Error logs reveal the specific cause of the issue:

# Nginx
sudo tail -50 /var/log/nginx/error.log
Apache
sudo tail -50 /var/log/apache2/error.log    # Ubuntu/Debian
sudo tail -50 /var/log/httpd/error_log       # CentOS/AlmaLinux
PHP-FPM
sudo tail -50 /var/log/php*-fpm.log

Common errors and solutions:

Step 5 — Check DNS

From your local machine:

dig example.com A +short

• If the result matches your server's IP (203.0.113.10) — DNS is correct.
• If the result is wrong or empty — DNS is misconfigured. See DNS Not Resolving.

Step 6 — Check the Firewall

Ensure ports 80 and 443 are open:

# UFW
sudo ufw status
firewalld
sudo firewall-cmd --list-all

If web ports are blocked:

# UFW
sudo ufw allow 80/tcp
sudo ufw allow 443/tcp
firewalld
sudo firewall-cmd --permanent --add-service=http
sudo firewall-cmd --permanent --add-service=https
sudo firewall-cmd --reload

See Firewall Blocking Legitimate Traffic.

Step 7 — Check Application Services

PHP-FPM

sudo systemctl status php*-fpm
sudo systemctl restart php*-fpm

Database

sudo systemctl status mysql     # or mariadb, postgresql
sudo systemctl restart mysql

If the database is down, your application will typically show a "database connection error."

Application-Specific

Check application logs in your web root or application directory for specific error messages.

Step 8 — Check Server Resources

# CPU and memory
htop
Disk space
df -h
Check for high I/O wait
vmstat 5 3

If resources are maxed out, see Slow Server Performance.

Quick Restart Sequence

If the cause is not immediately clear, try restarting services in order:

sudo systemctl restart php*-fpm
sudo systemctl restart nginx    # or apache2
sudo systemctl restart mysql    # or mariadb

What to Do Next

• DNS Not Resolving — Fix DNS issues.
• Slow Server Performance — Optimize a slow server.
• Firewall Blocking Legitimate Traffic — Fix firewall rules.
• How to Submit a Support Ticket — Get expert help.