Asus RT-AC68U and Asus RT-AC87U best settings as "access point"

[RamGuy]

Greetings,

I have recently "degraded" my Asus RT-AC68U and Asus RT-AC87U to plain "access points" as I'm currently running a Windows Server 2012 R2 installation as Active-Directory Domain Server, DHCP Server, DNS Server and Routing and Remote Access Service (RRAS) / NAT.

Currently spotting Asus Merlin 3.0.0.4_376.49_5 firmware on both I had the configured in "Access Point" mode with the RT-AC68U running 5.0GHz 80Hz only and the RT-AC87U running 2.4GHz 20/40Hz mode spotting the same SSID.


In terms of advanced / professional settings they ran:


2.4GHz (RT-AC87U)

Enable Radio: Yes
Enable Wireless Scheduler: No
Date to Enable Radio (week days): N/A
Time of Day to Enable Radio: N/A
Date to Enable Radio (weekend): N/A
Time of Day to Enable Radio: N/A
Set AP Isolated: No
Roaming Assisant: Disable
Enable IGMP Snooping: Enable
Multicast Rate (Mbps): Auto
Preamble Type: Short
AMPDU RTS: Enable
RTS Treshold: 2347
DTIM Interval: 3
Beacon Interval: 350
Enable TX Bursting: Enable
Enable WMM APSD: Enable
Reducing USB 3.0 interferance: Enable
Optimze AMPDU Aggregation: Enable
Optimze ACK Suppression: Enable
Turbo QAM: Enabled
Airtime Fairness: Disabled
Explict beamfoarming: Enabled
Universal beamforming: Enabled
Regulation mode: Off
TX Power Adjustment: 100%


5.0GHz (RT-AC87U)

Enable Radio: Yes
Enable Wireless Scheduler: No
Date to Enable Radio (week days): N/A
Time of Day to Enable Radio: N/A
Date to Enable Radio (weekend): N/A
Time of Day to Enable Radio: N/A
Set AP Isolated: No
Roaming Assisant: Yes (RSSI: -70 dB)
Enable IGMP Snooping: Enable
Multicast Rate (Mbps): OFDM 54
Preamble Type: Short
AMPDU RTS: Enable
RTS Treshold: 2347
DTIM Interval: 3
Beacon Interval: 350
Enable TX Bursting: Enable
Enable WMM APSD: Enable
Optimze AMPDU Aggregation: Enable
Optimze ACK Suppression: Enable
Airtime Fairness: Disabled
802.11ac beamforming: Enabled
Universal beamforming: Enabled
Regulation mode: 802.11h+d
TX Power Adjustment: 100%



I noticed that for instance my MacBook Pro 15" with retina display which is locaed about 6-8 meters from the router was starting to have some preformance issues over wireless and looking at the connection it was reporting 802.11ac (5GHz) at 90-130 mbps rates instead of its usual 650-1300 mbps.

I guess this might have something to due with me using the same SSID for both 2.4GHz and 5.0GHz so units like my brothers Asus G750 notebook being in the oposit side of the router (beamforming having a negative impact?) and all our phones now being iPhone 6 / 6 Plus and new iPad Air 2's all featuring 802.11ac is starting to lower the 5GHz preformance even though its set to 80Hz only.

I suspect beamforming is having a harder time with the access point located in the middle of the house and having various 802.11ac clients in various directions? I also expect going from the regular 2x MacBook Pros with 802.1ac over to having several 802.11ac devices is also causing some degration in terms of performance?


What would be the optimal configuration with 1x RT-AC68 and 1x RT-AC87 in terms of maximising performance? I'm considering to separate things into 2x SSID's, one for the MacBooks and the Asus laptop being the only computers in the need for 802.11ac bandwidth, and perhaps tossing in the iPad Air 2 considering it's being used for local HD-streaming from a Plex Server (20 MBps) and having all others on the second SSID.


Was thinking of doing it like this;

RT-AC68 running 2.4GHz (802.11 b/g/n) and 5.0GHz (802.11 ac-only) hosting SSID: Wireless Legacy (2.4GHz) and Wireless High-Preformance (5.0GHz)

RT-AC87 running 2.4GHz (802.11 n-only) and 5.0GHz (802.11 a/n/ac) hosting SSD: Wireless High Performance (2.4GH) and Wireless Legacy (5.0GHz).



Do you think this would be a good solution? Connecting everything to Wireless Legacy, and only the devices requiring high performance to the Wireless High Performance SSID? Optimizing all advanced settings for compatability on Wireless Legacy and optimizing towards best throughput on Wireless High Performance.

What would be the best advanced / professional settings for these two scenarios? I was thinking to go with something like this:

Wireless Legacy 2.4GHz:

Enable Radio: Yes
Enable Wireless Scheduler: No
Date to Enable Radio (week days): N/A
Time of Day to Enable Radio: N/A
Date to Enable Radio (weekend): N/A
Time of Day to Enable Radio: N/A
Set AP Isolated: No
Roaming Assisant: Disabled
Enable IGMP Snooping: Enable
Multicast Rate (Mbps): Auto
Preamble Type: Long
AMPDU RTS: Enable
RTS Treshold: 2347
DTIM Interval: 3
Beacon Interval: 350
Enable TX Bursting: Disabled
Enable WMM APSD: Enable
Optimze AMPDU Aggregation: Disabled
Optimze ACK Suppression: Disabled
Turbo QAM: Disabled
Airtime Fairness: Disabled
802.11ac beamforming: Disabled
Universal beamforming: Disabled
Regulation mode: Disabled
TX Power Adjustment: 100%


Wireless Legacy 5.0GHz:

Enable Radio: Yes
Enable Wireless Scheduler: No
Date to Enable Radio (week days): N/A
Time of Day to Enable Radio: N/A
Date to Enable Radio (weekend): N/A
Time of Day to Enable Radio: N/A
Set AP Isolated: No
Roaming Assisant: Yes (RSSI: -70 dB)
Enable IGMP Snooping: Enable
Multicast Rate (Mbps): Auto
Preamble Type: Long
AMPDU RTS: Enable
RTS Treshold: 2347
DTIM Interval: 3
Beacon Interval: 350
Enable TX Bursting: Disabled
Enable WMM APSD: Enable
Optimze AMPDU Aggregation: Disabled
Optimze ACK Suppression: Disabled
Airtime Fairness: Disabled
802.11ac beamforming: Disabled
Universal beamfoarming: Disabled
Regulation mode: 802.11h+d
TX Power Adjustment: 100%


Wireless High Perfomance 2.4GHz:

Enable Radio: Yes
Enable Wireless Scheduler: No
Date to Enable Radio (week days): N/A
Time of Day to Enable Radio: N/A
Date to Enable Radio (weekend): N/A
Time of Day to Enable Radio: N/A
Set AP Isolated: No
Roaming Assisant: Disabled
Enable IGMP Snooping: Enable
Multicast Rate (Mbps): Auto
Preamble Type: Short
AMPDU RTS: Enable
RTS Treshold: 2347
DTIM Interval: 3
Beacon Interval: 350
Enable TX Bursting: Enable
Enable WMM APSD: Enable
Optimze AMPDU Aggregation: Enable
Optimze ACK Suppression: Enable
Turbo QAM: Enable
Airtime Fairness: Disabled
802.11ac beamforming: Enable
Universal beamforming: Enable
Regulation mode: Disabled
TX Power Adjustment: 100%


Wireless High Performance 5.0GHz:


Enable Radio: Yes
Enable Wireless Scheduler: No
Date to Enable Radio (week days): N/A
Time of Day to Enable Radio: N/A
Date to Enable Radio (weekend): N/A
Time of Day to Enable Radio: N/A
Set AP Isolated: No
Roaming Assisant: Yes (RSSI: -70 dB)
Enable IGMP Snooping: Enable
Multicast Rate (Mbps): Auto
Preamble Type: Short
AMPDU RTS: Enable
RTS Treshold: 2347
DTIM Interval: 3
Beacon Interval: 350
Enable TX Bursting: Enable
Enable WMM APSD: Enable
Optimze AMPDU Aggregation: Enable
Optimze ACK Suppression: Enable
Airtime Fairness: Disabled
802.11ac beamforming: Enabled
Universal beamfoarming: Enabled
Regulation mode: 802.11h+d
TX Power Adjustment: 100%



What do you think? Would it be stupid to have both access points close by each other?

 

[L&LD]

Is there an executive summary of your problem and question?

 

[leszek]

Make it simple - use 2.4GHz for all legacy and 5.0GHz for all high perf connections. You're also didn't specify which channels you use on both. You might experiment with those depending on what site survey shows you. And finally disable IGMP snooping - it's too smart for its own good if you ever want to use DLNA.

 

[jegesq]

Agree with Lesek, keep it simple with legacy and most 11n clients on 2.4 and faster ac-capable clients on 5.0.

Also, from my experience, I've found that performance is better if the following options are not enabled:

Enable TX Bursting:-- Disable this
Enable WMM APSD: Disable this too.
Optimze AMPDU Aggregation: Disable
Optimze ACK Suppression: Disable

TX Burst really only benefits 11g; unless you're connecting older 11g devices, I would leave it off (although some people say it doesn't have any effect at all on 11n or 11ac, so they suggest leaving it on, but YMMV). The point is, it's only important if you're using 11g devices.

WMM ASD allows applications to drive power save modes in the client, and thus lets a client decide how often it needs to communicate with the router and how long it can remain asleep/hibernating. Some suggest that if you turn it off, this can add latency (because then your client has to use older legacy power schemes and some client devices may then not be able to control when they are awake or asleep). I find that my clients are managing their own power modes just fine without setting this to "enabled" so I leave it off.

As for "Optimizing AMPDU Aggregation", I've never seen a satisfactory answer anywhere on SNB to the question of whether it's better to leave it turned on or off. If you search here, you'll find some links to outside articles, but no one I've seen has given a really solid response as to "yes" or "no". The best explanation I've found for what "AMPDU aggregation is" and what it does that I've seen is found here: http://ergodicthoughts.blogspot.com/2012/02/difference-between-mpdu-msdu-ampdu-and.html, which makes clear that AMPDU is itself a form of header and packet aggregation designed for 802.11n. Some people say that they experience better streaming and performance with the setting "Enabled". I have seen no difference at all in my experience, so I leave mine "Off".

As far as ACK's and "Optimize ACK Suppression," you need to understand TCP, which uses a three way "handshake" to establish a connection. Basically, "SYN" is sent by the client first, and the server responds with "SYN-ACK", and then the client responds back with "ACK". At this point, you have a connection established in which the first "SYN" sets the connection parameter (sequence number) for one direction and it is acknowledged, and in the last two the connection parameter (sequence number) for the other direction is set and acknowledged, establishing full-duplex communication. ACK's are also used with "FIN" to terminate connections.

Sometimes packets get lost in transmission. Essentially, TCP has what some call a cumulative acknowledgment scheme, where the receiver sends an ACK signifying that the receiver has received all data preceding the acknowledged sequence number, but when packets are lost, another ACK is sent, requiring the server to resend the entire sequence again. This can lead to latency and signals dropping (or stuttering with video, etc.).

Wikipedia has this excellent summary:

The sender sets the sequence number field to the sequence number of the first payload byte in the segment's data field, and the receiver sends an acknowledgment specifying the sequence number of the next byte they expect to receive. For example, if a sending computer sends a packet containing four payload bytes with a sequence number field of 100, then the sequence numbers of the four payload bytes are 100, 101, 102 and 103. When this packet arrives at the receiving computer, it would send back an acknowledgment number of 104 since that is the sequence number of the next byte it expects to receive in the next packet.

In addition to cumulative acknowledgments, TCP receivers can also send selective acknowledgments to provide further information.

If the sender infers that data has been lost in the network, it retransmits the data.

I'm not going to get into the whole selective acknowledgment scheme here, but suffice it to say, "ACK Suppression" minimizes the return of duplicate ACKs that could otherwise cause latency and it minimizes redundancy.

As I said, I leave mine set to "Disabled" since I've never been able to detect any real difference either way, but you should play around with your's to see if you have better results with it set to "Enabled".

 

[primitivo]

I have myself RT-AC56U which is hidden in the closet and handling all day to day tasks including VPN. I would like to buy either RT-AC68U or RT-AC87U purely for Access Point use, but I am wondering if it is worth it, as I guess 5x cheaper AP should do the job as well.

Any advise?

 

[L&LD]

Let the RT-AC56U come out of the closet, if it wants to.

If you don't need another AP / router to extend the range, why bother?

 

[primitivo]

Let the RT-AC56U come out of the closet, if it wants to.

If you don't need another AP / router to extend the range, why bother?

I think I need, because all my ethernet cables are going to the closet, so I need a router there and it has to be Asus to run Merlin. I am also quite sure that AC68 or AC87 has better wifi coverage than AC56 with its built it antennas. I am leaning towards AC68 to use as AP.

 

[L&LD]

I agree the AC68U and the AC87U have potentially better range than the AC56U, but that is not too important depending on the area you need covered and the location of this network closet.

Is the main router centered in the area to be covered? Is it at least on the first floor and not in a basement?

If you cannot or will not move the router you have now to a more optimal location, why not consider a second AC56U as an AP. Positioned optimally, their range is nothing to be ashamed of. You may also consider a strictly wired router too and use the existing AC56U as an AP. Both of these options may save you some money.

But that depends on the answers to the questions above.

 

[primitivo]

I live in a pretty open space bungalow, so it might be that 2nd AC56 will do the job but in such case perhaps it's better to run 2nd ethernet cable to the central location and put a switch in the closet. My initial thoughts were that AC68 has much stronger WiFi coverage than AC56, since processing power is the same.