Significant drops in throughput at certain times of the day. This is generally due to a swelling of the client population with no adequate accommodation plan. This is where small optimizations in airtime utilization can really help.
Stuck wireless access points that aren't accepting clients at all. The lights are on, but nobody's home. Hard to catch unless there's a system of performance management in place constantly monitoring and measuring.
Excessive number of users on one access point while no users on adjacent access points. Could be a software issue or an AP placement issue. Some more data will help you isolate the WLAN issue.
Very high levels of management traffic utilization. In high density environments, every bit of airtime is precious. Learn to manage it properly.
802.11b low data rates are active. It may be time to cut the cord. Build a case and present the facts. Explain how a rising tide lifts all ships.
Excessive client/ radio retransmissions and low data rates from collisions, rogue APs or interfering neighboring networks.
Software issues in WLAN controllers. Talk to your vendor about maintenance releases and get up to date. Or in some cases full version upgrades are necessary. Often times new clients need the newest software.
Poorly tuned WLAN controller features, such as automated channel selection. Every environment is different so you can't just go with the defaults from your vendor. Get some help and fine tune your system to get the best results.
TxPwr too low. But how high is too high? You need performance data and analysis to truly know.
Too few access points resulting in coverage issues. Could be site survey time, but this won't help if the survey takes place after hours. You need data on what's happening in certain areas at peak usage times in order to best diagnose and prescribe a solution. You need to catch the problem in-the-act with a 24x7 monitoring system.
Incorrectly placed/positioned access points resulting in coverage issues.
Too many access points causing roaming issues and interference. Throwing APs at WLAN issues can cause more issues if not analyzed and planned out properly.
External sources of interference, such as motion detectors, patient monitors, wireless video cameras and neighboring networks.
Issues with wired network services, such as authentication, IP addresses, throughput and packet loss.
Errors in installation, such as a lack of DC power for access points, the incorrect use of antenna connectors or poorly placed/positioned access points may all cause WLAN issues.
Sources:www.7signal.com
