Questions about Dual-Band routers and using g/b/n/ac together

[Cyber Akuma]

I would like to mention that I am not too good with networking hardware.

I recently got a dual-band AC router (Asus RT-AC66U) and have been hearing some conflicting advice on how the dual-band works.

First of all, if I take for example a Dual-Band N router with two 300Mbps bands. That means that you have two lanes that go up to 300Mbps, and they don't add up to 600Mbps right? I have heard it mentioned both ways, and I always assumed they don't add up the same way having two 1GHhz cpus would not add up to having a single 2Ghz CPU.

Also, I was told that each band would have it's own SSID, but when I set up my router I only saw one SSID. I assumed it was automatic and the router manages which device goes on which band until I was told that I should be seeing two SSIDs instead of one (other than setting up WiFi security and assigning specific IPs to specific devices by network name I left it more or less on default settings, I am certain that the dual band option was enabled though).

And finally, I was told that this is important because having a b or g device on a n band would slow the band down to b/g speeds. Is this true? Does that mean that when AC devices are common, and I connect an old b or g device to it, that it will slow the entire band down to below even n speeds? Or that all the n devices I have now will mean there was no point in getting an AC router unless I get rid of them all? (or stick them on their own band?).

 

[GotNoRice]

SSIDs - You should at least have the option to use different SSIDs for the 2.4ghz and 5ghz networks, but there is nothing wrong with having them both share the same SSID.

Dual-Band means it broadcasts simultaneously on 2.4ghz and 5ghz, but you'll only be connecting to one or the other, not both at the same time. If they have the same SSID, whichever band has the higher signal strength at the time of connection will be used automatically.

Another thing, 802.11ac is 5Ghz ONLY. All 802.11ac wireless units will also broadcast on the 2.4Ghz band, but only using the 802.11n spec. When it comes to 2.4Ghz, 802.11n is as good as it gets. 2.4Ghz has so much better penetration through walls vs 5ghz that in real-world situations, unless you are line of site to the router/access point, you're almost always going to get a better signal and ultimately better speeds with 2.4Ghz. For that reason, AC is largely a gimmick compared to 802.11n. B or G devices will never slow down the AC band because B and G devices are 2.4Ghz only and AC is 5Ghz only. If you had a rare 802.11a client and connected to the 5Ghz band it might slow down other AC clients.

 

[Cyber Akuma]

So then it's pretty much attempting to mislead you when they claim a dual-band router with two 300Mbps bands is 600Mbps? You will never get a connection faster than 300Mbps on it? (And even that is under ideal conditions that you will likely never hit I assume)

What about b/g devices closing down the 2.4ghz band for other N devices however? And will they be slowing it down to b/g speeds?

What about N devices slowing down AC devices on the 5Ghz band?

 

[GotNoRice]

So then it's pretty much attempting to mislead you when they claim a dual-band router with two 300Mbps bands is 600Mbps? You will never get a connection faster than 300Mbps on it? (And even that is under ideal conditions that you will likely never hit I assume)

No you're confusing two totally different things. Each wireless channel is 20Mhz by default. That requires one transmitter and allows for 150Mbps. If your wireless router/access point has 2 transmitters and can use a 40Mhz channel, you can do 300Mbps. If your wireless router/access point has 3 transmitters and can use a 60Mhz channel, you can do 450Mbps, etc. This is "MIMO" and is in regards to the number of transmitters per frequency band. You'd still be connecting to either 2.4Ghz or 5Ghz, but not both at the same time. You have to have a MIMO (multiple transmitters) client in addition to a MIMO wireless router/access point, otherwise a non-MIMO N client will never connect faster than 150Mbps regardless of the capabilities of your wireless router/access point. You can do up to 600Mbps with 4 transmitters and an 80Mhz channel but I believe you can only do that on 5Ghz, considering that the entire usable 2.4Ghz frequency range is only 60Mhz...

It's going to come down to your particular router exactly how it handles older clients but B/G clients will generally slow down the 2.4Ghz network, especially B clients. N clients will slow down 5Ghz AC network vs pure AC but 5Ghz is so limited in terms of penetration through walls that unless you are <12 feet away with clear line of sight, you're probably going to be getting N speeds or slower with AC anyway.

 

[Cyber Akuma]

Sorry for the late reply.

So basically, you can only get 600Mbps+ speeds on the 5ghz band? And even then, your client will need multiple transmitters on it to connect on multiple channels in order to pull that off? But I was completely wrong in it just being a straight-up 300Mbps on the 2.4 and 5.0 ghz bands?