I'm using the 5ghz speed on my 6 plus and AppleTV. The modem connects straight into the Airport TC, then I have an Airport Express extending the network. The signal strength is great. Can't say that for the upload and download speed, as I'm only on ADSL 2, at the moment. Saying that it doesn't take long to load up pages on Safari and AppleTV works just the same as when I had a faster cable connection!
iPhone 6 plus, tested with 2.4 and 5.0 ghz WiFi. No difference in speed!
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iMac Ethernet connection to modem - ADSL2. Same speed as WiFi!
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with the ISP speeds you have, even a regular N is enough for you....maybe even WiFi-G lol.
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Anyone with less than 70Mbps ISP speed package won't see much improvement by investing in a AC-WiFi Router/Access Point. Stick with your WiFi-N and if use 5GHz when possible.
and thats like 98% of the people probably.
Also rather than naming both networks (2.4GHz and 5GHz) the same, name them separately because lots of time the devices don't switch up to 5GHz and stick with 2.4GHz.
I live in a high-rise and these days everyone has WiFi so we have like 40 access points that show up when looking for WiFi (all protected), however 99% are running on 2.4GHz so my 2.4GHz barely works, I have had no choice but to stick with 5GHz which works amazingly well, 1) has less coverage area, less noise, less overlapping with other networks.