Device unreachable after a VLAN change
One wrong tick (tagged vs untagged) and a whole department is offline. Classic trap.
Try this first
- 1Grab a laptop on cable and plug into the problem port. Do you get an IP? No IP = probably wrong VLAN on the port.
- 2In your switch controller, check that the device port is untagged on the correct VLAN. For PCs and printers almost always untagged.
- 3For APs: usually untagged on the management VLAN and tagged for the other SSIDs. Reversed = AP gone.
- 4Just made a change? Roll back that one change, verify it works, then redo step-by-step.
When to bring us in
VLAN work is best not done alone under pressure. Plan calmly with us and we document the right config so the second time is easier.
See also
- Wi-Fi drops randomly across the officeFirst rule out whether it is the access points or the internet connection itself. Different fix.
- One room or corner has no or bad Wi-FiNot always "add another AP"; often one is poorly positioned, or there is a metal wall in the way.
- Internet is suddenly slow for everyoneThree suspects: your provider, a colleague soaking the line, or a backup or update kicking in unexpectedly.
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