Help Diagnosing WiFi issue with Asus AC68 router and WiFi Adaptor

[rxallan]

I recently purchased the Asus PCE-AC68 WiFi adapter and RT-AC68 router thinking the WiFi AC speeds would be at least double those of my exiting 2.4GHz network. That did not pan out. I'm experiencing OK performance on the 2.4GHz side but on the 5GHz side the performance is brutal.

Symptoms on the 5GHz band:
I have my computer sitting directly next to the router
Computer shows the link at it's highest ratting of 1300mbps
Computer shows the signal strength at a strong -30db
So far so good,
Now I try to transfer a large file from my PC to my NAS (which is wired to the router), the throughput fluctuates between 2MB/s and 20MB/s, I was expecting a consistant throughput of at least 40MB/s like most of the reviews show.
When i hard wire my computer to the router I can write to the NAS at 50MB/s.
When I connect to my network on the 2.4GHz band I get a constant 18MB/s write speed to the NAS.

Transfer speeds:
Computer ----- cat5e ------ router ------ cat5e ------ NAS = 50 MB/s
Computer ----- 2.4GHz ------ router ------ cat5e ------ NAS = 18 MB/s
Computer ----- 5.1GHz------ router ------ cat5e ------ NAS = fluctuating between 2 and 20 MB/s

So the 2.4GHz side is fine,
Distance and line of sight are not a problem,
I've replaced the WiFi card once already,
My router is AC compatible,
I've tried the wifi card in different PCI slots,
I've tried the stock and Merlin FW on the router,

Help diagnosing the issue is welcome!

The transfer graphs look like this:

 

[jlake]

Try giving the 5 ghz a completely new SSID name. Use something that you've never used before. Then connect to it and run your test.

 

[rxallan]

Thanks for the suggestion.

The results:
Same as before. The transfer chugged away at 8MB/s for most of the time. It would rise to 18 at times, then fall to almost zero, then back to 8, ...etc until finished.

I tried changing the channel width to 80MHz, and the wireless mode to N+AC only. Same results.

I did the same on the 2.4GHz, change the channel width to 40MHz, and the wireless mode to N only and saw a performance gain. The transfer goes at a stable 20MB/s for the entire time.

 

[sinshiva]

not that i would consider this an acceptable solution, but what happens if you drop channel width to 20mhz on 5ghz ?

i know you said distance wasn't a problem, but how far away are we talking?

 

[rxallan]

Wow, interesting results.

When the channel width is set to 20MHz on the 5GHz band, the link rate drops from 1300mbps to 300mbps, but I get a constant 20MB/s transfer.

Whats going on here?

 

[sinshiva]

hm, when you set 40 or 80mhz on the router, have you tried forcing the wireless adapter to 40 or 80mhz only?

i have to admit, that was a wild guess, i don't own any ac products. hopefully somebody chimes in

have you tried moving the adapter to another pci slot? maybe a larger one?

 

[RMerlin]

Make sure QoS is disabled. I've seen it have some weird impact on LAN wireless transfers in the past.

 

[rxallan]

When locking the channel width to 80MHz, I get the same results as before - the transfer speed fluctuates between 0 and 18MB/s.

When channel width is locked to 40MHz I get very similar performance as to when it's locked to 20MHz. And in these two cases, I get very similar performance to the 2.4GHz network in that the transfer speed will stay at about 20MB/s for the duration of the transfer.

I've tried putting the WiFi card in different PCI slots, nothing changes.

QoS is off as well.

Does channel width have anything to how many antenna's are being used?

 

[sfx2000]

You've got the little antenna base thingy right?

Try moving it around to a different location - might be picking up noise from the computer itself.

Also - try keeping your 5GHz radio in automatic mode (A/N/AC)...

 

[rxallan]

I have the antenna base thing, but that's what's so confusing. The signal strength is great at -30db. It even increases to -20db during transfers. I've even tried placing the router directly next to the WiFi card. Nothing changes.

If the channel width is set to auto I get the fluctuations in transfer speed. The only decent performance on the 5GHz band is with a channel width of 20MHz.

 

[rxallan]

With this whole AC1900 idea (600mbps from the 2.4GHz side and 1300mbps from the 5GHz side), is is possible that if the 5GHz radios are somehow broken but I'm sitting connected to the 5GHz SSID I'm only using the 2.4GHz bands?

Would this explain why setting the channel width to 20MHz on the 5GHz bands gives me performance that's nearly identical to the those witnessed while on the 2.4GHz bands?

 

[L&LD]

No, that is impossible.

I think you're much too close to the router - it does need some distance to create the best signal to the client.

 

[sinshiva]

No, that is impossible.

I think you're much too close to the router - it does need some distance to create the best signal to the client.

concur; this is why i was asking about the distance. i was going to recommend either giving the ap/client some more separation or to try turning the power down on the 5ghz radio, maybe like 60mw

 

[L&LD]

That close I might even try 20mW Tx power.

 

[icece]

I have the antenna base thing, but that's what's so confusing. The signal strength is great at -30db. It even increases to -20db during transfers. I've even tried placing the router directly next to the WiFi card. Nothing changes.

If the channel width is set to auto I get the fluctuations in transfer speed. The only decent performance on the 5GHz band is with a channel width of 20MHz.

RSSI values of -30 to -20dbm or more might damage the wireless interface chipset.

 

[sinshiva]

That close I might even try 20mW Tx power.

at the range he's indicated, you're probably right lol

 

[rxallan]

Update:

Tonight, I went and picked up another RT-AC68 router to try to at lease rule it out.
Came home and set up said router, moved further away from the router than before, and witnessed the same poor results.
After pulling out some hair I decided to transfer the file across my network (connected to 5G WiFi all settings set to their defaults), but to another computer, not my NAS. And what do you know? 70MB/s transfer rate! How is this possible?

Why dosnt the 5G WiFi work with my NAS, but is rocket fast with random computer on my LAN?
Could this be a router settings problem or simply an issue with the NAS?
Questions...

Transfer speeds now look like this:
Computer ----- cat5e ------ router ------ cat5e ------ NAS = 50 MB/s
Computer ----- 2.4GHz ------ router ------ cat5e ------ NAS = 18 MB/s

Computer ----- 5.1GHz------ router ------ cat5e ------ NAS = fluctuating between 2 and 20 MB/s
Computer ----- 5.1GHz------ router ------ cat5e ------ Computer = 70 MB/s


Thanks for the help guys.

 

[RMerlin]

Update:

Tonight, I went and picked up another RT-AC68 router to try to at lease rule it out.
Came home and set up said router, moved further away from the router than before, and witnessed the same poor results.
After pulling out some hair I decided to transfer the file across my network (connected to 5G WiFi all settings set to their defaults), but to another computer, not my NAS. And what do you know? 70MB/s transfer rate! How is this possible?

Why dosnt the 5G WiFi work with my NAS, but is rocket fast with random computer on my LAN?
Could this be a router settings problem or simply an issue with the NAS?
Questions...

Transfer speeds now look like this:
Computer ----- cat5e ------ router ------ cat5e ------ NAS = 50 MB/s
Computer ----- 2.4GHz ------ router ------ cat5e ------ NAS = 18 MB/s

Computer ----- 5.1GHz------ router ------ cat5e ------ NAS = fluctuating between 2 and 20 MB/s
Computer ----- 5.1GHz------ router ------ cat5e ------ Computer = 70 MB/s


Thanks for the help guys.

If you had enabled it, disable Jumbo Frames on your NAS.

 

[speedingcheetah]

Update:

Tonight, I went and picked up another RT-AC68 router to try to at lease rule it out.
Came home and set up said router, moved further away from the router than before, and witnessed the same poor results.
After pulling out some hair I decided to transfer the file across my network (connected to 5G WiFi all settings set to their defaults), but to another computer, not my NAS. And what do you know? 70MB/s transfer rate! How is this possible?

Why dosnt the 5G WiFi work with my NAS, but is rocket fast with random computer on my LAN?
Could this be a router settings problem or simply an issue with the NAS?
Questions...

Transfer speeds now look like this:
Computer ----- cat5e ------ router ------ cat5e ------ NAS = 50 MB/s
Computer ----- 2.4GHz ------ router ------ cat5e ------ NAS = 18 MB/s

Computer ----- 5.1GHz------ router ------ cat5e ------ NAS = fluctuating between 2 and 20 MB/s
Computer ----- 5.1GHz------ router ------ cat5e ------ Computer = 70 MB/s


Thanks for the help guys.

What NAS are u using?

With my AC56U, I get full wire speed transfer 2 and from my FreeNAS system(and it uses ZFS file system and native compression). ~109MB's with cat6a cables.

Over 5g wifi....and my Intel AC7260.....I get around 40MB's transfer speeds.

 

[rxallan]

It's an inexpensive QNAP.
Nothing special.

I might try changing the ethernet cable between the NAS and router.
Never know...