Resolving DNS Issues with OpenVPN on macOS

If you're experiencing DNS resolution issues while connected to OpenVPN on macOS, where you can connect to the VPN but cannot resolve hostnames (like RDS endpoints or internal servers), this is typically caused by DNS server configuration problems. Symptoms OpenVPN client connects successfully Cannot ping or connect to servers using hostnames Error messages like "cannot resolve hostname: Unknown host" Adding entries to the hosts file works as a workaround Solution Configure your macOS to use Google's public DNS server (8.8.8.8) instead of your ISP's DNS server: Go to System Preferences > Network Select your Wi-Fi network Click "Advanced" Go to the "DNS" tab Add 8.8.8.8 as a DNS server Apply the changes Why This Happens Some ISP DNS servers (particularly AT&T) have issues resolving certain internal hostnames when connected through VPN. Using a public DNS server like Google's 8.8.8.8 bypasses these resolution problems. Additional Troubleshooting If the DNS configuration doesn't resolve the issue: Restart your laptop after making DNS changes Verify you're connecting to the correct VPN endpoint (cloud vs internal) Contact support to reset your VPN configuration if needed