RT-AC68U poor 5Ghz performance

joebloogs

Occasional Visitor
5Ghz on my Rt-AC68U is worse than 2.4Ghz and what ever i done has not improved it...(no complaints with 2.4Ghz)
Was running latest stock firmware up to now with no luck, so i switched over to Merlin 386.3.2 but still no joy!
Is there some secret setting i need to change to get the 5Ghz working?
I've done a site survey to check visible networks nearby and there are few 5Ghz signals but they are all VERY low.
Changed and tested different control channels, channel bandwidth, wireless mode but still no luck..
I am in the same room as the router 10-15 feet away with no walls in between, but 5Ghz performance is unstable & poor.

anyone have some advice?
 

OzarkEdge

Part of the Furniture
5Ghz on my Rt-AC68U is worse than 2.4Ghz and what ever i done has not improved it...(no complaints with 2.4Ghz)
Was running latest stock firmware up to now with no luck, so i switched over to Merlin 386.3.2 but still no joy!
Is there some secret setting i need to change to get the 5Ghz working?
I've done a site survey to check visible networks nearby and there are few 5Ghz signals but they are all VERY low.
Changed and tested different control channels, channel bandwidth, wireless mode but still no luck..
I am in the same room as the router 10-15 feet away with no walls in between, but 5Ghz performance is unstable & poor.

anyone have some advice?

The default WiFi settings should generally just work well enough, so narrow it down to trouble with the router hardware or trouble with your client(s) or some nearby radio interference on the 5.0 band.

OE
 

joebloogs

Occasional Visitor
The default WiFi settings should generally just work well enough, so narrow it down to trouble with the router hardware or trouble with your client(s) or some nearby radio interference on the 5.0 band.

OE
as already stated nearby 5Ghz signals are very weak so not sure if i can blame them...as for my clients...i tried with 3-4 different devices with no luck..
is there a way to check the hardware?
 

OzarkEdge

Part of the Furniture
as already stated nearby 5Ghz signals are very weak so not sure if i can blame them...as for my clients...i tried with 3-4 different devices with no luck..
is there a way to check the hardware?

Don't overlook any radio interference such as cordless peripheral devices or whatever nearby... the stuff you can't see and didn't mention.

A simple way to check the hardware is by being familiar with its setup and normal operation. Then you will know when its behaving weirdly. I would re-flash it, reset it, and configure it minimally from scratch. Then if you can not get a decent 5.0 client connection link rate of say 2x433=866 Mbps AC, suspect the hardware and try a different router.

OE
 

wouterv

Very Senior Member
Given that you start from factory defaults!
Common RT-AC68U settings that may help improve stability are:

Advanced Settings - Wireless - Professional - 2.4 GHz
Modulation Scheme: Up to MCS 7 (802.11n)
Airtime Fairness: Disable
Explicit Beamforming: Disable
Universal Beamforming: Disable

Advanced Settings - Wireless - Professional - 5 GHz
Airtime Fairness: Disable
Universal Beamforming: Disable

Besides the router, it can also be the network adapter drivers that play up.
In general older Intel wireless adapter drivers are known for issues. If we talk about PC's: check what network adapter is in there, visit the manufacturer website and search for the latest driver (Windows Update is not always up to date with wireless drivers).

Last but not least performance of 2.4 GHz and 5 GHz will be different for sure.
2.4 GHz is more powerful with a longer range, 5 GHz under ideal conditions gives a higher throughput but the range is limited.
Also, 5 GHz is very channel dependent, at my sons appartment 5 GHz is practically unusable due to radar detection (the router system log will tell you).
 

joebloogs

Occasional Visitor
Besides the router, it can also be the network adapter drivers that play up.
In general older Intel wireless adapter drivers are known for issues. If we talk about PC's: check what network adapter is in there, visit the manufacturer website and search for the latest driver (Windows Update is not always up to date with wireless drivers).

Last but not least performance of 2.4 GHz and 5 GHz will be different for sure.
2.4 GHz is more powerful with a longer range, 5 GHz under ideal conditions gives a higher throughput but the range is limited.
Also, 5 GHz is very channel dependent, at my sons appartment 5 GHz is practically unusable due to radar detection (the router system log will tell you).

my devices are all ipads & iphones with latest iOS versions installed, so that should rule out device driver issue...
I am aware of distance limitations of 5Ghz range, but i cannot get any signal improvement over 2.4Ghz even in the same room as my router!!
 

wouterv

Very Senior Member
Please confirm, as suggested before, that you start with the router from factory defaults, basically only setting the router username / password and SSID's and passphrases.
Then experiment with 5 GHz channels, at first set the channel to 36, 40, 44 or 48 (the non DFS channels).
 

joebloogs

Occasional Visitor
I have factory reset my router with latest Merlin to factory defaults, Initializing all the settings, and clearing all the data log for AiProtection, Traffic Analyzer, and Web History.
I must note I am using wifi Sweetspots app on my devices to measure wifi signal quality..
tested each non DFS channels manually with no joy, then went back to auto (excluding DFS channels) router usually transmits from 40/44
tested yesterday from various parts of my open plan living room and i can hardly receive a signal over 70Mbps..at one point, the furthest part of the room (25ft away from router) i managed an average of 160Mbps BUT i couldn't go above 70Mbps today....

I am beginning to think this might be an iOS (apple) issue...i have ipad pro, ipad mini 5, iphone 6S+ and few other older ipads all running latest iOS 15.2 and all give me the above results..

then i decided to do some tests using the wife's Android Samsung A71 phone and was shocked to get up to 180Mbps (-39dBm) under same conditions my apple devices couldn't deliver!!
Samsung phone does not go below 120Mbps on 5Ghz band in the same room!!

how does one explain this?


by the way...attached is the result of my site survey scan
 

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wouterv

Very Senior Member
Probably the Samsung has a 2x2 wireless interface, were the iPhone (at least the 6s) has a 1x1 interface.
More parallel data streams mean a higher throughput.
Have a look at the Wireless Log of the router to look at performance from the router point of view.

Regarding the site survey, it shows the lower channels of the 5 GHz band are congested, probably the router scales down from 80 MHz to 40 MHz or maybe even 20 MHz, that will really slow down throughput.
The Wireless Log of the router will tell you.

[EDIT] The iPhone 6s has a 2x2 wireless interface, but for quite sure another chip then the Samsung.
 
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SoCalReviews

Very Senior Member
This was my experience with most of my aging RT-AC68Us. The Wifi still worked but the 5Ghz performance was becoming unbearable... poor range, inconsistent connections and a tendency for most of my Wifi devices to flip to the 2.4Ghz band SSID and not go back if it was available even at short distances.
 
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Tech9

Part of the Furniture
Something is perhaps wrong with this router because I have 3x different versions of it in form of RT-AC66U B1, RT-AC68U and RT-AC1900P and all of them push consistently >350Mbps on 5GHz ch36 @80MHz to common 2-stream AC client. My RT-AC1900P unit is the one with upgraded flat antennas (2017 model), the same as AC86U antennas. It also has almost the same range as AC86U - better than older brothers.
 

joebloogs

Occasional Visitor
@joebloogs, is this the same RT-AC68U router you had issues with in 2017? It's time to replace it, I guess. :rolleyes:


yes M8...same router...now that you mention it, i went & had a look at my previous posts and found out i had 5Ghz speed issues back in 2017...
also had a look at the date i made those posts and i think i know the problem now...

When i first noticed this problem back in 2017 was when i had just moved to a new property up on the hills overlooking a wast populated area (which my previous property was, in town)
In my country, great majority of internet connections are supplied to end users through wireless connections and i recently found out my new location on the hills,
is the area where most of the transmitters receiving massive bandwidth from the closest city and transmitting to the town below are located...
although signal levels on my GUI showing 5Ghz activity is low, there is plenty off 5Ghz traffic around me, so i doubt i will ever get a decent 5Ghz signal in my house..
 

wouterv

Very Senior Member
...
is the area where most of the transmitters receiving massive bandwidth from the closest city and transmitting to the town below are located...
although signal levels on my GUI showing 5Ghz activity is low, there is plenty off 5Ghz traffic around me, so i doubt i will ever get a decent 5Ghz signal in my house..
I think I told you such a few posts up, after you showed your site survey
 

Tech9

Part of the Furniture
the area where most of the transmitters receiving massive bandwidth from the closest city and transmitting to the town below are located

They use different frequency. Unlikely to affect your Wi-Fi. I would replace the router with something more modern like RT-AX68U. The new routers deal with interference better, reach further and will push more data even to your existing clients. Look for local deals and solve the problem.
 

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