Can't reach another device on your network? Here's how to diagnose and fix subnet problems.

Step 1: Check Basic Connectivity

  1. Ping the gateway: ping 192.168.1.1
  2. Ping the target: ping 192.168.1.100
  3. Check your IP: ipconfig (Windows) or ip a (Linux/Mac)

Common Issues

Issue 1: Wrong Subnet Mask

Symptom: Can reach some IPs but not others.
Fix: Check subnet mask is consistent on all devices.

Issue 2: Different Subnets

Symptom: Can't reach any device.
Check: Are both devices on the same subnet? 192.168.1.100/24 and 192.168.2.100 cannot talk directly.

Issue 3: Gateway Not Set

Symptom: Local works, internet doesn't.
Fix: Configure default gateway on the device.

Diagnose with ARP

ARP cache shows what your device sees:
arp -a (Windows)
arp -n (Linux/Mac)

If you can ping but ARP shows nothing, the device isn't replying.

Tools to Use

👉 Verify Your Subnet