Warehouse Roaming and Channel Plan Troubleshooting
After a channel plan change, a distribution center reports intermittent scanner disconnects. The warehouse has 24 APs, metal racking, and high ceilings. ExtremeCloud IQ shows three APs in aisle 7 with retry rates above 35%, channel utilization above 70% on 5 GHz, and one AP with 84 clients while two neighbors have 18 and 22. Clients are a mix of handheld scanners (2.4 GHz only), laptops (5 GHz capable), and fixed-mounted tablets. The site uses 40 MHz channels on 5 GHz because 'more bandwidth is better'. Users say drops happen when forklifts move between aisles. The network team has access to Client 360, Device 360, alarms, and RF quality dashboards. The change was made last Tuesday at 02:00; no firmware change occurred. The team wants to avoid another site-wide outage.
1. What evidence would you collect first from ExtremeCloud IQ, and how would you separate a client problem from an RF problem?
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Start with Client 360 for the affected scanners to see disconnect reasons, roaming history, RSSI, SNR, retry counts, and whether failures cluster at specific times or APs. Use Device 360 and RF quality dashboards for the aisle 7 APs to compare channel utilization, retry rate, client count, transmit power, and channel width. Check the 2.4 GHz radio as well, because the scanners are 2.4 GHz-only and a 5 GHz channel change should not directly affect them unless band steering or load balancing is pushing other clients in ways that change airtime. The 84-client AP versus 18 and 22 neighbors points to load imbalance, while 40 MHz channels in a metal-rich warehouse point to co-channel interference. Separate the two by checking whether scanner disconnects correlate with the overloaded AP or with high retry on all three APs.
2. What is the most likely root cause, and what change would you pilot first?
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The strongest hypothesis is excessive channel width and unbalanced client load. 40 MHz channels on 5 GHz in a warehouse with metal racking reduce the number of clean channels and increase co-channel and adjacent-channel interference, which shows up as high retry and utilization. The 84-client AP is also carrying far more load than its neighbors, so roaming and load balancing are likely uneven. Pilot on aisle 7 first: move 5 GHz to 20 MHz channels, review transmit power so coverage overlaps without sticky clients, enable or tune band steering and load balancing for capable clients, and verify that 2.4 GHz settings still support the scanners. Do not change all 24 APs at once. Compare retry rate, utilization, client distribution, and scanner disconnect alarms before and after the pilot.
3. How would you confirm the fix worked and decide whether to roll it back?
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Define success before the change: lower retry rate, lower channel utilization, more even client distribution, and fewer scanner disconnect alarms in aisle 7. After the pilot, use Client 360 to compare disconnect and roaming behavior for the same scanner population, and use Device 360 to compare RF metrics at the same time of day, since warehouse activity varies by shift. Check that 2.4 GHz-only scanners still associate and that laptops are not being forced onto unusable channels. If retry and disconnects improve without new coverage holes, extend the change in small batches. If scanners lose coverage or retries rise on neighboring APs, roll back the aisle 7 settings and test a narrower change, such as power adjustment alone.