WiFi slow when students roam

[jnesci]

I have a school with 166 AP's/2200 students. 1 AP per room. Using only 5Ghz, 2.4 shut down. 20Mhz channels. 2 ssid's, one for school devices, one is BYOD & guest. When the bell rings and students change class the entire wireless network comes to a standstill and throughput is reduced from 150Mbps to 1-2Mbps. Network stays this way for the first 10-15 minutes of each class. The wired network is unaffected and runs fine. If anyone has seen this problem and knows a solution, I would like to hear how you resolved it.

[jnesci]

I just wanted to add an update that I got from a sales engineer that fixed our problem. Basically, there were some radio profile changes that weren't too earth shattering, but the main issue we had come from GTAC suggestions. Since our schools were 1-to-1, an AP in each classroom, we were always told to turn down the radio power to isolate each room so there was no bleed-through into other rooms. Our AP power was set to either 2 or 3. Slightly more in larger rooms.

Issue: When the bell would ring and students were roaming through the halls with their devices (mostly phones) still connected to the WIFI, their devices would lose connections from the room they left and re-authenticate to the next room they passed as they walked down the hall. This was a constant process as they moved throughout the building. Authenticate, move, drop, re-connect to next room, re-authenticate, move, drop, and so on. This constant movement of 2100 kids and 200 staff throughout the building flooded the wireless network with all this traffic and caused everything to freeze.

The change: We set the radio power to a floor of 10. This allowed wireless roaming and pre-caching to work properly and hand off clients from AP to AP without dropping and having to re-authenticate. We made the change on a Friday and on Monday our wireless network was working 100% better. It was a night and day difference. Our after-action meeting with the sales engineer that helped us was great. He asked why we had set the radios so low, and I told him that there were several tickets where this GTAC recommendation was made. I sent him the ticket numbers and he said he knew the GTAC manager and was going to call him and discuss this problem. Hopefully the distribution of this bad information was stopped.  

[Jan_Reister]

Fascinating issue, the solution could lay in the answers to Christoph's questions.

[Christoph_S]

Hello @jnesci,

Too many variables may be affecting wireless communications to list, for starters:

1 - Type of wireless devices: Chromebook, Windows , IOS, etc.... (There are many Chromebook articles that you can reference)

2 - Are you using the default radio profile?

3 - Are DFS channels enabled?

4 - Are the radios transmitting at full power?

5 - Are SSID data rate thresholds configured?

6 - Are broadcast and directed probe settings configured?

7 - Is cast traffic affecting the APs?

etc. 

I would recommend that you reach out to the GTAC team so that we may thoroughly investigate this issue. 

BR,

[jnesci]

I have had a GTAC case open for 2 months, two different engineers have looked at this and there has been no improvement. As of yesterday the latest change was to remove a QOS setting on a Guest User profile in case it is "leaking" through to the other user profiles. Evidently this has been seen before. Each variable you listed has been checked without change (except #5 which we are doing now). I'm wondering if anyone else has seen this issue and what the resolution was.