This guide explains how to troubleshoot a website that is not working on a self-managed VPS, even though:
The VPS is accessible via SSH
The hosting provider confirms no infrastructure issues
The server is online
Only the website is failing
1. Initial Quick Checks
If your VPS is accessible via SSH or Emergency Console, you should run:
uptime
free -m
df -h
systemctl --failed
What to Look For
High load average
Memory exhaustion
Disk space at 100%
Failed system services
These four commands often reveal the root cause within minutes.
2. Website Not Loading at All
Symptom
“This site can’t be reached”
Browser timeout
Connection refused
Step 1: Check Web Server Status
For Apache:
systemctl status apache2
or:
systemctl status httpd
For Nginx:
systemctl status nginx
If stopped:
systemctl restart nginx
If it fails to start:
journalctl -xe
Step 2: Verify Ports 80 and 443 Are Listening
ss -tulnp | grep :80
ss -tulnp | grep :443
If no output appears, the web server is not listening.
Step 3: Check Firewall Rules
If using UFW:
ufw status
If using iptables:
iptables -L -n
Ensure ports 80 (HTTP) and 443 (HTTPS) are open.
Step 4: Verify DNS
From your local machine:
nslookup yourdomain.com
Confirm:
Correct IP address;
DNS propagation complete - if records are changed there might be 1-24 hours propagation (time depends on the changed DNS record);
A record properly configured and your domain is pointed to your VPS IP address.
3. 500 Internal Server Error
Common Causes
PHP crash
Permission errors
Corrupt
.htaccessDatabase issues
Disk full
Check Web Server Logs
Apache:
tail -f /var/log/apache2/error.log
Nginx:
tail -f /var/log/nginx/error.log
Logs typically provide the exact cause.
Check PHP-FPM
systemctl status php8.1-fpm
If stopped:
systemctl restart php8.1-fpm
Also review PHP logs:
/var/log/php8.1-fpm.log
Check File Permissions
Correct typical configuration:
chown -R www-data:www-data /var/www/html chmod -R 755 /var/www/html
Incorrect ownership is a very common issue after deployments or file transfers.
Check Disk Space
df -h
If disk usage is 100%, remove unnecessary files such as:
Old backups
Large logs
Cache directories
4. 502 Bad Gateway (Common with Nginx)
Most Common Cause
PHP-FPM is not running.
Restart services:
systemctl restart php8.1-fpm systemctl restart nginx
Also verify the socket path in your Nginx configuration matches:
/run/php/php8.1-fpm.sock
5. 503 Service Unavailable
Possible Causes
Server overload
Maintenance mode
PHP max_children limit reached
Check PHP pool configuration:
grep max_children /etc/php/8.1/fpm/pool.d/www.conf
Increase the value if necessary and restart PHP-FPM.
6. Database Connection Errors
Example Message
“Error establishing database connection”
Step 1: Check Database Service
systemctl status mysql
or
systemctl status mariadb
Restart if necessary:
systemctl restart mysql
Step 2: Verify Credentials
Check application configuration files such as:
.envwp-config.phpconfig.php
Test database login manually:
mysql -u dbuser -p
Step 3: Check for Corruption
mysqlcheck -u root -p --all-databases
7. Website Extremely Slow
Check System Load
top
Look for:
High CPU usage
Excessive PHP processes
MySQL consuming 100% CPU
Memory exhaustion
Check Memory and Swap
free -m
If swap usage is high, the server likely lacks sufficient RAM.
Possible solutions:
Upgrade VPS RAM
Optimize MySQL configuration
Reduce PHP worker processes
Conclusion
If your VPS is accessible but the website is down, the issue is almost always related to:
A stopped service
Resource exhaustion
Misconfiguration
Application-level failure
Systematically checking services, logs, disk space, and resource usage will resolve the majority of incidents quickly.