SonicWall firewall: DHCP relay not forwarding
By Sai Kiran Pandrala · reviewed by Sai Kiran Pandrala, Editor Last verified: 2026-05-30
| Vendor | SonicWall |
|---|---|
| Operating system | SonicOS |
| Category | IP / Network Issue |
| Skill level | Intermediate to advanced |
| DIY-able? | Yes with CLI access; some scenarios need SonicWall Support + RMA. |
What this guide covers
Fix DHCP relay not forwarding on a SonicWall 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
show interface X0
show status
When the issue persists
- Open a SonicWall Support case with the tech-support bundle.
- Provide the timeline + recent changes.
Frequently asked questions
Will this work on my specific SonicOS version?
The procedure reflects current SonicOS behaviour. Older releases may need minor syntax adjustments, use the CLI help (? or tab-completion) to verify.
Should I open a SonicWall Support 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 SonicWall official documentation?
https://www.sonicwall.com/support/knowledge-base/. 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 SonicWall fix guides → /sonicwall/
- All vendor guides → /vendors/
Related fixes
Related guides worth a look while you sort this one out:
- SonicWall switch: DHCP relay not forwarding
- SonicWall firewall: DHCP clients not receiving IP
- Best SonicWall firewall for branch office
- Best SonicWall firewall for enterprise data centre
- Best SonicWall firewall for retail store
- Best SonicWall firewall for SD-WAN deployment
References
- SonicWall support portal: https://www.sonicwall.com/support
- SonicWall knowledge base: https://www.sonicwall.com/support/knowledge-base/
- SonicWall security advisories: https://psirt.global.sonicwall.com
- Open a case: https://www.mysonicwall.com
Reference material, not professional advice. Validate against your specific SonicOS version and test in a non-production environment before applying.
What changed recently?
Fault diagnosis on a SonicWall 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.
Safety + preconditions
Before any work on a SonicWall device:
- Unplug from mains for any internal-access procedure.
- Discharge stored energy (capacitors in PSUs, residual battery charge) per manufacturer guidance.
- Use ESD-safe handling for boards and modules, no carpet, no wool sleeves.
- Avoid moisture; never apply liquids near vents or connectors.
- If you smell smoke, see scorch marks, or feel uneven heat, stop and escalate.
How to confirm it's actually fixed
On a SonicWall 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.
Escalation guide
For a SonicWall device, the right escalation depends on impact:
- Cosmetic / minor: log a ticket via the SonicWall app or web portal. Response 1-3 business days.
- Mid-impact: phone support. Have your serial number ready.
- Critical (production down, safety issue): in-person dealer / TAC visit. Bring proof of purchase.
- Out of warranty: third-party repair shop with manufacturer-certified technicians.
More frequently asked questions
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.
Will the procedure work on the international variant?
Some features and firmware paths are region-locked. Check the model spec sheet to confirm your variant supports the menu option referenced. If you're outside the US/EU, look for the regional support portal.
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.
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.
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.