Palo Alto Networks firewall: DHCP relay not forwarding
By Sai Kiran Pandrala · reviewed by Sai Kiran Pandrala, Editor Last verified: 2026-05-30
| Vendor | Palo Alto Networks |
|---|---|
| Operating system | PAN-OS |
| Category | IP / Network Issue |
| Skill level | Intermediate to advanced |
| DIY-able? | Yes with CLI access; some scenarios need Palo Alto TAC + RMA. |
What this guide covers
Fix DHCP relay not forwarding on a Palo Alto Networks firewall.
Step-by-step
- Confirm the helper-address / relay-IP is configured.
- Ensure the DHCP server IS reachable from the relay.
- Verify no ACL is blocking UDP 67/68.
- Capture relay traffic to confirm where it stops.
CLI / commands
show interface all
show interface ethernet1/1
show system state filter sys.s1.p*
When the issue persists
- Open a Palo Alto TAC case with the tech-support bundle.
- Provide the timeline + recent changes.
Frequently asked questions
Will this work on my specific PAN-OS version?
The procedure reflects current PAN-OS behaviour. Older releases may need minor syntax adjustments: use the CLI help (? or tab-completion) to verify.
Should I open a Palo Alto TAC case immediately?
Open one if you suspect hardware failure or the symptom persists after a maintenance-window reload. Make sure your support entitlement is active first.
Where can I find the Palo Alto Networks official documentation?
https://knowledgebase.paloaltonetworks.com, search the product family + feature name.
Is this procedure safe in production?
Test in a lab or maintenance window first. Capture pre-change state so you can roll back.
Related guides
- All Palo Alto Networks fix guides → /paloalto/
- All vendor guides → /vendors/
Related fixes
Related guides worth a look while you sort this one out:
- Palo Alto Networks firewall: DHCP clients not receiving IP
- Best Palo Alto Networks firewall for branch office
- Best Palo Alto Networks firewall for enterprise data centre
- Best Palo Alto Networks firewall for retail store
- Best Palo Alto Networks firewall for SD-WAN deployment
- Best Palo Alto Networks firewall for small office
References
- Palo Alto Networks support portal: https://support.paloaltonetworks.com
- Palo Alto Networks knowledge base: https://knowledgebase.paloaltonetworks.com
- Palo Alto Networks security advisories: https://security.paloaltonetworks.com
- Open a case: https://support.paloaltonetworks.com/Support/Index
Reference material, not professional advice. Validate against your specific PAN-OS version and test in a non-production environment before applying.
What changed recently?
Fault diagnosis on a Palo device goes faster when you map the symptom to a recent change:
- Did firmware update in the last 7 days?
- Did the network (router, ISP, VPN) change?
- Was the device moved physically?
- Did paired devices (phone, hub, app) update?
- Were any accessories swapped in or out?
The answer narrows the root cause to a manageable subset.
Before you start
A few things to confirm so the Palo device fix goes cleanly:
- Latest firmware downloaded if you're going to update.
- Warranty + support contract status checked. opening sealed parts may void it.
- Backup of current configuration (where applicable) taken.
- Spare parts on hand if you anticipate replacement.
- Adequate workspace, lighting, and time, rushing causes regressions.
How to confirm it's actually fixed
On a Palo device, the test is rarely "reboot and see". Use this list:
- Active reproduction: trigger the original failure path on purpose.
- Indirect reproduction: do an activity that would expose the same subsystem.
- Status indicator review: every LED / display / app status should be green.
- 24-hour soak: leave the device under normal load overnight; check the next morning.
- Telemetry check: review the device or app's diagnostic log for new error entries.
When to call Palo support instead
Escalate if:
- The same symptom returns within 24 hours of a clean fix.
- You see physical damage (burn marks, swollen battery, cracked PCB).
- The device is in warranty and a hardware replacement is the cheaper outcome.
- Repair requires specialised tools you don't own (alignment jigs, calibration software).
- Following the official path keeps the warranty intact, which matters more than the time spent.
More frequently asked questions
How long does this fix usually take?
Most users complete the steps in 20-45 minutes the first time, and 5-10 minutes on subsequent runs once the menu paths are familiar.
Why is this happening on a brand-new unit?
Out-of-box defects do occur. If you've owned the device under 30 days and the symptom persists after a factory reset, escalate to the seller for replacement under DOA terms before opening a manufacturer support case.
Should I update firmware first or last?
Update firmware first if a release note specifically mentions your symptom. Otherwise, finish the troubleshooting flow first, then update; that way you can isolate whether the update or the underlying fix solved it.
Is it safe to apply during business hours?
If the device is in production use, apply during a scheduled maintenance window. Most procedures need 2-15 minutes of downtime. Capture pre-change state so you can roll back if needed.
Can I roll this back if something breaks?
Yes for software-level changes (firmware rollback, config rollback). Hardware changes are usually one-way. Always back up settings before starting.