Why does my wifi speed fluctuate?

[binarydad]

Connected to a N66U, downloading over 5Ghz N from a local share. The ups and downs seem to always follow a pattern. What is causing this? Interference? There is some congestion according to wifi analyzers. Thanks.

 

[thiggins]

Connected to a N66U, downloading over 5Ghz N from a local share. The ups and downs seem to always follow a pattern. What is causing this? Interference? There is some congestion according to wifi analyzers. Thanks.

Can you do the transfer via Ethernet and compare?
What are you transferring?

 

[binarydad]

Can you do the transfer via Ethernet and compare?
What are you transferring?

The speed over ethernet is just fine, about 100-115 MBps. I did another transfer shortly after and the speed was more consistent. I was wondering if this has to do with interference management in the WiFi.

I'm transferring a single large file.

 

[thiggins]

You said there is "congestion". Sharing bandwidth with other users that are also using high bandwidth would produce the results you are seeing.

You can try changing channels, using 1, 6 or 11. If there is a network using another channel that is close by (strong signal) consider using that channel vs. whichever of 1, 6 or 11 is closest. Otherwise they will appear as noise, which can lower your throughput.

 

[jeff3820]

I've had ~4 RT-N66Us over the years and the 5GHz channel is buggy is all of them...same symptoms. Also, Android units that get disconnected on 5GHz and require a router reboot to resolve. Same issue with every Asus firmware and Merlin firmware. I concluded it was the 5GHz hardware in the RT-N66U. Every RT-N66U performed faster/more consistently on 2.4GHz most of the time.I eventually moved to the RT-AC68U and those are bulletproof...all of them work great on all radios.

Not the answer you were looking for...

 

[binarydad]

You said there is "congestion". Sharing bandwidth with other users that are also using high bandwidth would produce the results you are seeing.

You can try changing channels, using 1, 6 or 11. If there is a network using another channel that is close by (strong signal) consider using that channel vs. whichever of 1, 6 or 11 is closest. Otherwise they will appear as noise, which can lower your throughput.

No other clients, just me, unless something else was downloading a firmware/update/whatever, though it wasn't likely.

I guess I meant to say "interference". There are several other 40mhz and 80mhz WAPs near me (and on the same channels as mine). I can't really avoid them by getting on a clear channel.

When another WAP is broadcasting, I assume as part of the protocol that others on the same channel would wait or do a round-robin approach? I'm curious about the pattern of ups and downs. If there was some sort of radio error, I would assume the ups and downs would be more sporadic and random. I'm trying to understand the wireless protocol when it comes to transfers and interference. Thanks.

 

[jim769]

Strange i have had 2 N66 and the 5Ghz band worked great on both.

 

[binarydad]

Strange i have had 2 N66 and the 5Ghz band worked great on both.

Yeah, mine's been rock solid over the years, though I am considering an Orbi mainly to get more coverage.

 

[TomS.]

The width of the pulses is roughly the same. Could be a buffer, TCP window, or wireless beacon? There's alot of moving parts between that Task Manager screen and the wireless radios.

What does Intel's Proset Wireless show? Can you increase the logging details? Perhaps someone can recommend a tool to get radio level stats.

OP wrote they were on 5GHz 802.11n . Are you able to disable all 802.11b/g compatibility on your AP and clients? There was a presentation I saw not too long ago about negative b/g compatibility impacts on throughput at the London Olympics.

[edited to add disable b/g]

 

[thiggins]

I'm trying to understand the wireless protocol when it comes to transfers and interference. Thanks.

Wi-Fi is a shared medium. All devices (APs and clients aka STAs) on the same channel share the same bandwidth.

Only one device can use the channel at a time, whether it is on your WLAN or another WLAN using the same channel. So when another WLAN is using the channel, your WLAN needs to wait, which translates to lower bandwidth. If

I suggest you still try another channel(s). The # of WLANs isn't as important as how busy they are. You might be able to find a less busy channel.

If you can move up to an AC router and devices, you may see an improvement. 802.11ac packs more data into its alloted airtime, so is much more efficient.

 

[binarydad]

Wi-Fi is a shared medium. All devices (APs and clients aka STAs) on the same channel share the same bandwidth.

Only one device can use the channel at a time, whether it is on your WLAN or another WLAN using the same channel. So when another WLAN is using the channel, your WLAN needs to wait, which translates to lower bandwidth. If

I suggest you still try another channel(s). The # of WLANs isn't as important as how busy they are. You might be able to find a less busy channel.

If you can move up to an AC router and devices, you may see an improvement. 802.11ac packs more data into its alloted airtime, so is much more efficient.

Thank you. This was what I wanted to confirm regarding how it works. In my case, the lower channels on my 5ghz band had less WAPs, but the signal was worse. When I left my router on "auto" for channel selection, it kept choosing a higher-frequency channel with more WAPs. Maybe the chatter is less, even with the higher number of WAPs.

I've noticed when doing speedtests on my phone, sometimes the speed will drop to 0mbps for about a 0.25 to 1 second, then come back up to full speed (60-100mbps). Is this also normal behavior? It'll do this on either frequency. I assume this is just chatter from other WAPs on the same frequency, causing my transfer to stop briefly?

Yes, I'm drooling over getting an Orbi to not only get myself into the world of AC but also expand my coverage.

 

[thiggins]

I've noticed when doing speedtests on my phone, sometimes the speed will drop to 0mbps for about a 0.25 to 1 second, then come back up to full speed (60-100mbps). Is this also normal behavior?

It's hard to tell what is "normal" with Wi-Fi. Could be neighboring networks, could be the phone OS, could be the app.

Airtime management and data aggregation has gotten a lot better in 11ac. You should see a difference when you change. But remember, you need to change BOTH ends of the connection to get the full benefit of 11ac.