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Fix a switch that will not forward

We'll check power, cables, VLANs, and configuration—so the switch forwards traffic or we tell you when to call support.

Troubleshooting · Wi‑Fi & networking
10–25 min
What you'll need
  • Network switch
  • Ethernet cables
Step 1 of 5

Quick triage — pick your path

Quick triage — pick your path

Choose the option that matches what you see. You can jump straight to that section.

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Steps

Goal: Check power, links, VLAN, and configuration so the switch forwards traffic.

  • Confirm the switch has power and all link lights are on.
  • If the switch uses VLANs, confirm devices are on the same VLAN.
  • Restart the switch. Check for network loops.
  • Good: The switch forwards traffic. Bad: The switch still will not forward—reset or call support.

Goal: Confirm power and link lights.

  • Check the switch is powered. Check each connected port has a link light.
  • Good: Power on, links on. Bad: No power or no links—check cables.

VLAN check

Goal: Confirm VLAN configuration.

  • If the switch uses VLANs, devices must be on the same VLAN to communicate (unless configured otherwise).
  • Good: VLAN correct. Bad: VLAN wrong—fix config.

When to get help

Call the manufacturer if:

  • The switch still will not forward after checking power, VLANs, and resetting.
  • The switch may be faulty.

Verification

  • Devices connected through the switch can communicate.
  • The uplink to the router shows a link.
  • No broadcast storms or loops.

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Check power and links Confirm switch powered, all link lights on.
  2. Check VLAN Confirm devices on same VLAN if applicable.
  3. Restart Power-cycle the switch.
  4. Reset Factory reset the switch.
  5. Call support Manufacturer support if all steps fail.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • Switch model
  • VLAN configuration (if applicable)
  • Steps already tried

Does the switch have power and are link lights on?

No power or no links means no forwarding.

Check power and link lights. Good: power on, links on. Bad: no power or no links—check cables and power.

Yes No

You can change your answer later.

Fix power and cables

Power the switch. Check cables are seated. When links come up, check if traffic forwards.

Done

Does the switch use VLANs? Are devices on the same VLAN?

Different VLANs block communication.

Check VLAN config. Good: devices on same VLAN or VLANs correctly configured. Bad: devices on different VLANs—fix config.

Yes / N/A No

You can change your answer later.

Fix VLAN configuration

Put both devices on the same VLAN, or configure inter-VLAN routing. Check if traffic forwards.

Done

Restart the switch

Power-cycle the switch. Good: switch forwards. Bad: still will not forward—check for loop, reset, or call support.

Done

Reviewed by Blackbox Atlas

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