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Wireless troubleshooting — four ways it looks broken
Enterprise Advanced 5 devices 5 checked tasks 100 points Plan lab
Everything is cabled and nothing works. The WLAN is shut, the client has the wrong key, the client VLAN is not the one the switch trunks, and one AP cannot find the controller. Each of them reads as "wireless is down" and each is one line. You build it in a browser, type real commands at each device, and every task below is
checked against the running configuration — so you find out it is wrong before anybody else does.
Open this lab in the simulator
The simulator runs in your browser with nothing to install. This lab is part of the full simulator: open it free for 7 days with a new account, then with a plan. It needs an account, which keeps your progress.
The scenario
Everything is cabled and nothing works. The WLAN is shut, the client has the wrong key, the client VLAN is not the one the switch trunks, and one AP cannot find the controller. Each of them reads as "wireless is down" and each is one line.
Your role: a network engineer on the enterprise team. Level: Advanced Done when: all 5 goals show as passed (100 points).
Network status
Devices: 1 switch, 2 routers, 2 PCs, cabled as drawn. No Layer 1 or Layer 2 faults: every link is connected and up. SW1 starts with addresses (V30 10.30.0.1/24) and VLAN 30 already configured. Wired-PC is a host with 10.30.0.10/24, gateway 10.30.0.1. WLC1, AP1 start with an empty configuration. Known problems
The network worked and now does not: the scenario above says what users report. The cause is a configuration fault, not a cable. Find it with show commands (interfaces, routes, neighbours, running-config) before you change anything; fix only what is wrong. Goals
The WLAN is enabled rather than shut (20 pts) Its client VLAN is 30 — the one the switch actually trunks (25 pts) The client is associated, so the key matches (25 pts) …and it landed in VLAN 30 (15 pts) The access point is still joined to the controller (15 pts) The activity, in order
The WLAN is enabled rather than shut Why: Each goal is a state the lab can check on the running device. Verify with: show running-config Its client VLAN is 30 — the one the switch actually trunks Why: Each goal is a state the lab can check on the running device. Verify with: show running-config The client is associated, so the key matches Why: Each goal is a state the lab can check on the running device. Verify with: show running-config …and it landed in VLAN 30 Why: Each goal is a state the lab can check on the running device. Verify with: show running-config The access point is still joined to the controller Why: Each goal is a state the lab can check on the running device. Verify with: show running-config Tips
Work in the order given: later goals depend on the earlier ones. After every change, run the verify command before moving on; do not guess. Stuck? Read the verify output first. It names the interface, neighbour or route that is wrong. Why this matters
Everything is cabled and nothing works. The WLAN is shut, the client has the wrong key, the client VLAN is not the one the switch trunks, and one AP cannot find the controller. Each of them reads as "wireless is down" and each is one line.
What you will be able to do
The WLAN is enabled rather than shut
Its client VLAN is 30 — the one the switch actually trunks
The client is associated, so the key matches
…and it landed in VLAN 30
The network
Catalyst 9300-24, Catalyst 9800-L, Catalyst CW9176I, Laptop, PC — 5 devices in all, already cabled.
Gi1/0/1 Gi0/0/0 Gi1/0/2 Gi0 Gi1/0/10 Fa0 Wireless0 Wireless0 SW1 WLC1 AP1 Laptop-1 Wired-PC 10.30.0.10/24 · gw 10.30.0.1 Drawn from this lab: devices, cables, ports and the addresses already set. Device Model Address already set
SW1 Catalyst 9300-24 configure it WLC1 Catalyst 9800-L configure it AP1 Catalyst CW9176I configure it Laptop-1 Laptop configure it Wired-PC PC 10.30.0.10 / 255.255.255.0 gw 10.30.0.1
Cabling
SW1 Gi1/0/1 ↔ WLC1 Gi0/0/0 SW1 Gi1/0/2 ↔ AP1 Gi0 SW1 Gi1/0/10 ↔ Wired-PC Fa0 AP1 Wireless0 ↔ Laptop-1 Wireless0
What is configured at the start
These are already configured when the lab opens — including, where this is a troubleshooting lab, the fault itself:
SW1 vlan 30
name GUEST
exit
interface GigabitEthernet1/0/2
switchport trunk encapsulation dot1q
switchport mode trunk
switchport trunk allowed vlan 1,30
exit
interface GigabitEthernet1/0/10
switchport mode access
switchport access vlan 30
exit
ip routing
interface Vlan30
ip address 10.30.0.1 255.255.255.0
no shutdown
exit WLC1 wlan GUEST 1 GUEST-WIFI
client vlan 99
security wpa wpa2
security wpa akm psk
security wpa psk set-key ascii 0 rightkey123
exit Laptop-1 netsh wlan connect ssid=GUEST-WIFI key=wrongkey999 Tasks, and how each one is checked
Every task is decided by reading the live network — a neighbour in FULL, a ping that succeeds, a line in the running configuration — not by looking for a keyword you typed. The same command shows you what the lab sees.
# Task Pts How to verify it yourself
1 The WLAN is enabled rather than shut 20 Checked automatically against the device’s live state (wlanUp). 2 Its client VLAN is 30 — the one the switch actually trunks 25 Checked automatically against the device’s live state (wlanUp). 3 The client is associated, so the key matches 25 Checked automatically against the device’s live state (wifiAssoc). 4 …and it landed in VLAN 30 15 Checked automatically against the device’s live state (wifiVlan). 5 The access point is still joined to the controller 15 Checked automatically against the device’s live state (apJoined).
Stuck? Ask the coach
Tell the coach what you see or what you tried. It gives you a hint, not the answer, the way a senior engineer would. Included with a free trial or any plan.
Ask the coach
Reference solution
Try it yourself first — the lab checks your work either way. This is one configuration that makes every task pass, device by device:
WLC1 wlan GUEST 1 GUEST-WIFI
client vlan 30
no shutdown
exit Laptop-1 netsh wlan connect ssid=GUEST-WIFI key=rightkey123 Where this is examined
This lab practises these topics in the zNetLaB certification courses:
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