Poor iPhone WiFi Roaming Choices

Question

Poor iPhone WiFi Roaming Choices

I use a small network of 802.11ac Airport Extremes for network coverage to a Comcast 100 Mb/s Internet connection. I use both 2.4 GHz and 5 GHz WiFi networks (on separate SSIDS since I can then manually force roaming to the 5 GHz network) configured at 20 MHz and 40 MHz channels.

When roaming between access points I often find that the iPhone chooses to connect to the 2.4 GHz network rather than the 5 GHz network. Speed tests reveal that performance on the 2 GHz network is about 10x worse (5-8 Mb/s vs 60-70 Mb/s) than on the 5 GHz network - yet the iPhone consistently chooses the 2 Ghz network when making a roaming decision. While I can solve this by manually choosing the 5 GHz SSID, it is annoying.

This appears to happen much less frequently with various recent MacBooks on the same network.

I conjecture that the iPhone's WiFi roaming algorithm is tuned for max RSSI alone, ignoring the difference in noise floor or channel width and certainly ignoring other performance metrics.

BTW - when I asked Apple Support about this ... they told me that I was configuring the APs wrong .. they should use the same SSID. If I did that I would lose the ability to force use of the higher performance network.

Anyone have a secret fix to this?

iPhone 6 Plus, iOS 8.3

Posted on May 25, 2015 8:50 AM

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Answer 1

Best reply

jjkraw

Level 2

449 points

May 25, 2015 9:12 AM in response to leadfromfront

What OS X has that iOS does not is the ability to list WiFi networks in a preference order (System Preferences -> Network -> WiFi -> Advanced).

What I've noticed is that if the phone is in the house and I've picked my 5GHz network (I have different names as you do) it will stick with it. Even if I turn off the WiFi on the phone, when I turn it back on it seems to prefer the last connected network.

If I leave the house and then come back, I always connect to the 2.4GHz network. I've watched this within Settings -> WiFi and the 2.4GHz network always appears first. So if it is a matter of which network it finds first or the signal strength at the distance in my garage (2.4GHz has a better range than 5), I can understand how it would pick the 2.4 network.

I'd suggest sending Apple some feedback (http://www.apple.com/feedback/) to ask for a feature similar to OS X's ordering preference.

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Answer 2

May 25, 2015 9:55 AM in response to jjkraw

Good point. Had not thought of search order as being part of the solution as well.

I have sent in a comment to Apple already.

I do think the solution needs to be larger than search order .. but preference order could help.

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Answer 3

jjkraw

Level 2

449 points

May 25, 2015 10:04 AM in response to leadfromfront

I can amend my reply above to add this: I just left the house with the phone connected to 5GHz. While I was out, I did not connect to any other WiFi networks. When I arrived, I was back on 5GHz again. So there does seem to be some sort of "stickiness" for the last network, at least in this case.

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Answer 4

May 25, 2015 11:10 AM in response to leadfromfront

Do some 2.4ghz/5ghz wifi analysis

Can I safely assume you've set the channel spans/overlap properly? 1,6,11 on 2.4 and 5 has it's own scheme

The 5ghz network has about half the range of 2.4, so it makes sense that phones would see the 2.4 network more often.

Make sure there's not any sort of interference from channels, microwaves, nearby celltowers, etc.

Run Win- InSSIDer or Mac- Netspot and take a look at what is in the wifi. Post screenshots and I can try to spot any underlying issues.

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