Wifi Issues Yosemite 10.10.5

Hold down Option while you click on the Wi-Fi Icon on the menuBar. You get a display like this:

What do you get for Channel, PHY mode?

RSSI/signal strength?

Transmit rate?

and most important, how many other networks do you see?

You are using the much-less crowded 5GHz band, and have a double-wide 40MHz channel. Your RSSI (signal) to noise is (-95 -56) = -39, a very strong signal. Your Transmit rate bears this out at a remarkable 324 Mbits/sec.

you should be having no problems, Even with all those competing Networks, because most will be fighting for the crowded and interference-prone 5GHz band.

PROVIDED your Router is using Channel selection "automatic" in the 5GHz band. This allows the Router to "sniff" the various Channels at Startup, and choose the one with least interference and the best reception. This is why every debugging procedure includes "cycle the power on your Router" as an early step.

There are some additional tools that you can initiate and leave open in a corner of your desktop. They are available through "Network Diagnostic button when you Option-clcik the Wi-Fi Icon. Let it run through the first part, it probably won't find anything deadly, and let it proceed for about a minute to this screen:

Now from the Window menu, choose "Performance". a window opens with a real-time graph of the Transmit rate, signal Quality, and the third graph shows both signal and noise in different colors. Don't close any of theses. Just leave the graph in a corner of your desktop and go about your business. ALL of these indicators should stay very close to their present Values. If any "takes a dive" you want to look into it.

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Selecting the "Scan" window will give you a better picture of who you are fighting for bandwidth, and what Channel in which band they are currently using.

Use Wireless Diagnostics to help you resolve Wi-Fi issues on your Mac - Apple Support

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Well the MacBook Pro is probably sending the most data at a gulp of any device.

What does it say about Dropouts?

What do you get when you click those other Info buttons?

Conflicting Country codes may influence what frequencies are allowed. and that other item suggests it hates your Router setup.

Click on the [√] Monitor my connection, and use the Window menu to select Performance and Scan and see if you can learn anything more about this.

On the Scan window, see if any other Router is using your 5GHz channel.

On the Performance window, see if your signal drops suddenly, slowly fades over time, or disappears.

I have the feeling something is not right in 10.10.5. Here is what I get in Wireless diagnostics monitor. Since 10.10.5 (or better some days after upgrading) I need a much stronger signal than before to have an acceptable connection. I used this MBP mid 2012 non-retina for almost 2,5 years basically in the same environments and now it is not working anymore. Any help would be greatly appreciated.

Although it may ultimately be blamed on Software, the graphs you show do not currently support that conclusion.

That graph says the signal strength (RSSI) deteriorated greatly (green line on bottom graph) when you made the move from 1 meter to 4 meters. You need about 20 points difference between signal and noise to have a good connection, and that difference disappears, making a good data rate impossible.

The "quality" graphs tracks the signal strength very appropriately, and the "Data Rate" adjusts itself appropriately as well, frantically trying to get down to a speed where it can work reliably, and ultimately failing.

This looks to me like Hardware problems, but it is not clear if the Router, the Wi-Fi card or its antenna is the problem (or if you were suddenly asking it to transmit through three feet of solid concrete). This does not look like a software issue to me.

excutive summary: You lost your signal.

If not caused by the Router or the distance, Poor signal strength could be caused by a disconnected antenna wire or a bad Wi-Fi card.

I should just note - I have this exact same issue with my late 2012 15" Retina MBP...same symptoms...same kind of diagnostics. The interwebs and forums report the MBP as having on again/off again issues.

My MBP was humming along fine, no WiFI issues, when 10.10.5 came along, all of the sudden, very erratic WiFi, slowing to a crawl, jumping back up again, all over the place. I upgraded to 10.11 El Capitan, but it's the same issue. I can clear plists, and use all the tools recommended, and it works for a few minutes, then degrades.

This is very MBP specific - my 2014 Retina 5K iMac is a scream machine at the same time on the same WiFi network. My IOS devices also have no WiFi issues.

Chaz

In my case it seems like it might be a hardware issue after all. A couple of times I could improve reception by moving the screen and pressing firmly on the plastic clutch on the bottom (this is the antenna). Will report back once I am completely sure that this is not a coincidence.