I was setting up a Windows domain controller on my Proxmox lab for an Active Directory test... and I made a dumb mistake that broke the whole thing for hours.
❌ Problem: I had my DC on one VLAN (.10 subnet) and my workstations on another (.20), but I forgot to route DHCP properly through pfSense.
🔍 Symptom: Workstations couldn’t get IPs. I thought it was DNS. Then I thought it was the firewall.
✅ Fix: I needed to allow DHCP relay between VLANs and set the proper firewall rules. Plus, manually assigned the gateway and DNS when debugging.
💡 Lesson: Always test VLAN-to-VLAN rules early. And packet capture in pfSense is your best friend.