Fix "Network Unreachable"

Understanding the Error

The system cannot find a route to the destination network.

Quick Diagnosis

# Check routing table
ip route show
route -n

# Check default gateway
ip route | grep default

# Ping gateway
ping -c 4 YOUR_GATEWAY_IP

Fix 1: Check Network Interface Status

ip link show
# Interface should be UP
sudo ip link set eth0 up

# Check IP assignment
ip addr show

Fix 2: Restart Networking

# Ubuntu/Debian
sudo systemctl restart networking

# CentOS/RHEL
sudo systemctl restart network

# Or using nmcli
sudo nmcli networking off
sudo nmcli networking on

Fix 3: Renew DHCP Lease

sudo dhclient -v eth0
# Or
sudo dhcpcd eth0

Fix 4: Add Default Gateway Manually

# Find gateway from provider info
sudo ip route add default via GATEWAY_IP

# Make permanent (Ubuntu netplan example)
network:
  ethernets:
    eth0:
      dhcp4: no
      addresses: [YOUR_IP/24]
      gateway4: GATEWAY_IP
      nameservers:
        addresses: [8.8.8.8, 8.8.4.4]

Fix 5: Check Firewall Rules

sudo iptables -L -n
# Look for DROP or REJECT rules on OUTPUT chain

Fix 6: IPv6 vs IPv4

Try forcing IPv4:

ping -4 google.com
curl -4 http://example.com

Disable IPv6 if problematic:

# Add to /etc/sysctl.conf
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
sudo sysctl -p

For VPS After Reinstall

Sometimes network config resets. Check with Hostxpeed support for correct network configuration or use the "Network Reset" option in control panel.