9800-80 pair running 17.9.4a and APSP8 (upgraded about a month ago). Upon investigating after slowness/connection complaints from the professor of a 150-seat lecture hall where 9166s are installed, I realized that every single client in the room was connected at 2.4 GHz. I realized that RRM had set the 2.4 GHz radios higher than the 5 GHz ones, which I corrected, but clients still wouldn't connect at 5 GHz. I visited the room and my iPhone 12 Mini and Dell laptop with Intel AX211 both connected at 2.4 GHz, even though I sat right under an AP.
We have an identical lecture hall next door, and last week I saw that clients were connecting at 5 GHz, but now all are connecting at 2.4 GHz. It seems like this could become a bigger issue.
I took an OTA, packet capture at the WLC, RA trace, and tech support from the AP before and after rebooting the APs. Upon rebooting, all the clients are connecting at 5 GHz. Spectrum analysis looked clean. I opened a TAC case yesterday and they are analyzing the information collected, but I thought I'd post to see if anyone else was experiencing this.
Here's the client distribution in the two rooms. The ones named BPB-130 are the ones that were rebooted, the ones in BPB-131 have not been rebooted yet. Notice the opposite trend of 2.4 vs 5 GHz client counts.
