2014 Mac Mini Low Network Link Speed & High WiFi Latency

[wildcat1]

Hi there

I've been trying to resolve this for a few days now and after a lot of testing need some help. Specifically I have 2 x Asus AC routers, 1 AC3100 (acting as an AP) and 1 AC88u acting as a router. The actual topology of this looks something like this

AC3100 (running as 802.11n AC Access Point) --> Hardwired to wall port --> Hardwired to Patch Panel --> Hardwired to Cisco Business Switch --> Hardwired to AC88u (providing DHCP for all devices and 2.4 Ghz WiFi for older devices) --> Hardwired to Cable Modem for Internet Connectivity.

Recently I was seeing some issues with playing video on an ATV 4th Gen through the Plex app (not saying Plex app may not be an issue here BTW). Specifically buffering and general things you would associate with high latency. This ATV 4th gen is WiFi connected to the AC3100. So I started to do some testing and specifically when pinging that ATV from another WiFi device was seeing ping times between 1ms and 500+ ms. I then installed a free network tools app on the ATV an pinged from it to another wireless device (MBP) and saw the same thing, high latency. However pings from those wireless devices to the outside world (testing a ping to Google for example) was around 12ms as expected.

I then moved onto to testing with Mac Mini's (2 x 2014 units to test with) and again was seeing the same thing. Some results of these tests are below. What I also noticed was that these 2014 Mac Mini's that I borrowed to test with are only showing link speeds of 11 Mbit/s whereas even the old MBP (limited to 802.11n) was showing 450 Mbit/s in the same location ! The Mini's advanced network info (option key on WiFi symbol in bar) showed PHY mode of 802.11AC and TX Rate of 1300 Mbps but again link speed is 11 Mbit/s.

I have tried changing everything from channel, to wireless mode (separating to N/AC only), channel bandwidth etc but cannot get those tester mini's to connect at anything above 11 Mbit/s.

I also tried enabling 5GHz on the AC88u and clearing every other device (than the mini's) off of the network and still same things, higher latency and never shows a link speed above 11 Mbit/s.

I know some of the devices appear to be doing the WiFi power saving mode whereby they will have a higher latency while not directly in use to save power and then when doing something latency reduces etc but although I expect that on say ATV or iPhone, I don't expect to see that so much on MBP and mini which never change even when in use.

So my questions really are, what could I be missing in terms of settings on router, mac etc ? Also why can I not seem to get beyond 11 Mbit/s link speed on the mini's at AC (even though TX rate showing 1300 Mbps) when if I connect to an older 802.11n router I can get them to show 450 Mbit/s link speed ?

Thanks so much for any help you can offer with this. The high latency is only when pinging WiFi to WiFi devices or wired to WiFi, WiFi to Wired latency is low as expected on LAN (under 0.3 ms). The mini's are seeing a signal strength of 92% so would not appear to be any issues there. Currently connecting on 80Mhz channel. Summary of my test results are below:

Also posted this on the official Apple Support forums as well



Tests From Mac Mini Tester #1

Mac Mini Tester #1 WiFi to MBP (both connected to AC3100)

10 packets transmitted, 10 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 2.367/189.994/1006.106/291.943 ms


Mac Mini Tester #1 WiFi to Mac Mini Tester 2 WiFi (both connected to AC3100)

10 packets transmitted, 10 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 3.291/324.676/1002.906/312.427 ms


Mac Mini Tester #1 WiFi to Google.com
10 packets transmitted, 10 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 12.741/14.200/17.425/1.380 ms​

Tests From Mac Mini Tester #2

Mac Mini Tester #2 WiFi to MBP (both connected to AC3100)

10 packets transmitted, 10 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 2.379/176.682/1002.944/327.199 ms

Mac Mini Tester #2 WiFi to Mac Mini Tester 1 WiFi (both connected to AC3100)

10 packets transmitted, 10 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 23.865/248.639/617.065/223.895 ms

Mac Mini Tester #1 WiFi to Google.com

10 packets transmitted, 10 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 12.884/17.047/27.873/4.670 ms​

Tests From MBP

MBP To Mac Mini Tester #1 WiFi (both connected to AC3100)

10 packets transmitted, 10 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 4.773/179.994/621.168/215.714 ms


MBP To Mac Mini Tester #2 WiFi (both connected to AC3100)

10 packets transmitted, 10 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 17.887/212.556/600.719/171.421 ms


MBP To Google.com

10 packets transmitted, 10 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 12.848/16.568/23.079/3.344 ms​

 

[jpietrzak8]

I know some of the devices appear to be doing the WiFi power saving mode whereby they will have a higher latency while not directly in use to save power and then when doing something latency reduces etc but although I expect that on say ATV or iPhone, I don't expect to see that so much on MBP and mini which never change even when in use.

Actually, I believe this may be the case. Apple has been getting very aggressive about reducing power usage on all their machines, and powering down radios on an idle machine is an easy win. The wide variance between min and max values looks that way to me too. I think you could prove this by checking the individual packets, and see if the maximum latency occurs only on the first few packets, rather than occurring randomly.

(Also, you might want to check playing videos on the Macs vs. the ATV; I wouldn't be so quick to rule out there being an issue on the ATV itself.)