Open Radar

 
+++ Duplicate of 22436921 (Open) +++


Summary:
Using an 802.11ac capable wifi access point, the iMac is totally unable to join the 5 GHz network when in 3x3 MIMO mode (HT80).
Setting AP to use 2x2 MIMO (HT40) will allow iMac to join wireless network. However, there are lot's of packet drops and partly extremely high latency pinging the local gateway. Sometimes data transfer is completely lost while OSX wifi icon indicates the connection still persists.

Steps to Reproduce:
1. Use a Ubiquiti Networks wireless access point of type "UniFi AP AC".
2. Setup 5 GHz network using HT80 to allow for 3x3 MIMO. It doesn't matter wether the network has WPA2 encryption enabled or does not use any encryption at all.
3. Try to join the 5 GHz network with an iMac14,2.
4. Change wireless access point settings to use HT40 instead of HT80 to change to 2x2 MIMO mode.
5. Try to join the 5 GHz network with an iMac14,2.
6. Have a ping running to a local destination. You will see packet drops and after some minutes even complete packet loss for a while.

Expected Results:
iMac14,2 should be able to join 802.11ac 3x3 MIMO (HT80) wireless networks.
iMac14,2 should not have any packet loss on 802.11ac 2x2 MIMO (HT40) wireless networks.

Actual Results:
iMac14,2 is unable to join 802.11ac 3x3 MIMO (HT80) wireless networks.
iMac14,2 has packet loss on 802.11ac 2x2 MIMO (HT40) wireless networks. During packet loss the wireless noise is extremely high (nearly until 0 dBm).

Version:
Tested with OS X 10.10.5 on iMac14,2.
Tested with OS X 10.11 Beta (15A263a) on iMac14,2.

Notes:


Configuration:
Using 3rd party wireless network access point: Ubiquiti Networks - type "UniFi AP AC".

iMac14,2_jp_802.11ac_wireless_3x3MIMO.spx - configuration file has been successfully uploaded.

Attachments:
'2015.08.23_16-11-10-GMT+2.wdmon', 'iMac14,2_jp_802.11ac_wireless_3x3MIMO.spx', 'wifi.log', 'WirelessDiagnostics_BASIC_DGKP30N0F8JC_2015-08-23_16.05.04.tar.gz' and 'WirelessDiagnostics_DGKP30N0F8JC_2015-08-23_16.08.59.tar.gz' were successfully uploaded.