If you experience bad unit performance like low throughput, please consider to follow these steps.
1. If throughput seems sluggish, check to see how many SonicPoints you have on one interface. In large deployments it's advisable to spread them across more than one. Try to limit the interfaces to a 4-to-1 subscription ratio. For example, if you have a 100Mbps, you can safely attach up to 20 SonicPoints to it and expect reasonable performance. It is NOT advisable to use the same SSID for the 802.11bg and the 802.11a radios, as clients with tri-band cards may experience disconnect issues, hence name them separately.
2. Please remember when running mixed mode (802.11a/b/g/n) if one device using 802.11g standard connects to the wireless, the 802.11n clients will run at "g" speed.
3. Please upgrade the firmware of the SonicPoints to the latest one. To do so, go to the diag.html page of your firewall (http:///diag.html example - http://192.168.168.168/diag.html), scroll down to the wireless section and click on "Update All SonicPoint's Firmware".
4. Please consider to check your WAN's MTU for the most suitable one. Test it with 1404.
5. For test reasons please disable all security services on WLAN zone. To do so, go to Network > Zones and click the Configure button. See if your throughput is getting better, if so, consider to re-enable the security services one by one and test everytime to understand which service is limiting your throughput.
6. Go to SonicPoints and press the configure button on the right hand side, next to the desired SonicPoint. Next, choose Radio Settings and under Mode choose either 2.4GHz or 5GHz in "n Only" mode. Then, choose Radio Band to Wide 40MHz Channel. Channels are to be chosen on the basis of RF score each of them gets - the higher, the better. Tick: Enable Short Guard Interval (This would avoid any kind of data loss from wireless interference) or Enable Aggregation (it increases throughput of 802.11n by sending multiple data frames in a single transmission). Under Authentication Type choose WPA2-PSK, Cipher type AES.
7. On the Advanced tab: set Preamble Length to Short, this is recommended for improved throughput. The Beacon Interval value depends on the number of VAP's. For each VAP you add, you need to increase Beacon Interval by 100.
8. Temporarily disable wireless security and test the connection with different wireless devices.