Fluctuating Signals - what it means? how to fix?

[SunrisePro]

Hello folks,

I've had our new router (Linksys WRT1900AC) for about a week now. It works way better than the old Netgear R6100 but in the last couple of days I noticed some sketchy connectivity with the 2.45ghz signal.

Last night, after it seemed that no one in the house could connect to 2.4ghz I opened up Acrylic and saw that it's signal was fluctuating wildly and for channel it showed two - 7, 11. I went into the wifi settings and changed the channel from Automatic to 11 and it has been very steady since.

This morning I figured I'd take a look at what's going on & the 2.4ghz signal (dark purple) is nice & steady - yet stronger than the 5ghz signal (aqua). It's also a lot steadier. The wildly fluctuating pink signal is from the Fios router, which I avoid using (haven't tried turning it off yet but I need it to connect to the cable). Also, I observed the signals while our microwave was on & did not detect any effect.

Here are my questions:

1) why would a signal fluctuate so much and does picking a channel make that big a difference?
2) shouldn't the 5ghz signal be stronger? I was under the impression that 5ghz had better speed and range.

thanks!

 

[sfx2000]

It's an oddity that I've personally observed with this router - couple of things to check and try...

2.4GHz Radio Config - change from Auto to B/G/N-Mixed
2.4GHz Radio Config - Change Channel Width from 40/20 to 20MHz only

Auto enables VHT20/VHT40 mode (TurboQAM/QAM256), this is a non-standard mode of operation in 2.4GHz, basically it's trying to do 11ac in 2.4, which isn't allowed in 11ac...

Changing from 40/20 on the channel widths to 20MHz only - you might have a neighbor stepping on either the primary or secondary channels, and this will compromise the overall signal and performance on your WLAN.

Give it it try... changing those two settings for me worked wonders...

 

[sfx2000]

Also, one last thing...

Noticed in your screen shot that you're using WPA2-Mixed - try changing that to WPA2-AES - with WPA2-Mixed, the groupwise keying is TKIP, which is not good for non-unicast traffic, e.g. Multicast/Anycast, and with most modern clients these days, they should all be supporting WPA2-AES anyways.

 

[L&LD]

1) Yes. On auto, it is constantly trying to decide (and it can only do that by switching) and that impedes performance.

2) You don't mention how far you are and how many obstacles are between you and the router, but generally, the 5GHz band is weaker vs. the 2.4GHz band at any normal distance. Even as the throughput is greater for the 5GHz band too (assuming 40MHz or larger channel widths and sufficient signal to utilize them with).

Try the suggestions that sfx2000 offers too and see if you can get even better performance.

Hello folks,

I've had our new router (Linksys WRT1900AC) for about a week now. It works way better than the old Netgear R6100 but in the last couple of days I noticed some sketchy connectivity with the 2.45ghz signal.

Last night, after it seemed that no one in the house could connect to 2.4ghz I opened up Acrylic and saw that it's signal was fluctuating wildly and for channel it showed two - 7, 11. I went into the wifi settings and changed the channel from Automatic to 11 and it has been very steady since.

This morning I figured I'd take a look at what's going on & the 2.4ghz signal (dark purple) is nice & steady - yet stronger than the 5ghz signal (aqua). It's also a lot steadier. The wildly fluctuating pink signal is from the Fios router, which I avoid using (haven't tried turning it off yet but I need it to connect to the cable). Also, I observed the signals while our microwave was on & did not detect any effect.

Here are my questions:

1) why would a signal fluctuate so much and does picking a channel make that big a difference?
2) shouldn't the 5ghz signal be stronger? I was under the impression that 5ghz had better speed and range.

thanks!

 

[TonyH]

1) Yes. On auto, it is constantly trying to decide (and it can only do that by switching) and that impedes performance.

2) You don't mention how far you are and how many obstacles are between you and the router, but generally, the 5GHz band is weaker vs. the 2.4GHz band at any normal distance. Even as the throughput is greater for the 5GHz band too (assuming 40MHz or larger channel widths and sufficient signal to utilize them with).

Try the suggestions that sfx2000 offers too and see if you can get even better performance.

Whether you believe or not, weather condition can cause that as well. Lately in our area, we have daily afternoon
thunder storms occurring with heavy down pour some times with hail stones as big as golf ball. During this periods
I can see signal level acting up.

 

[L&LD]

I believe it. That is why Auto doesn't make sense for that and other reasons.

 

[SunrisePro]

Thanks - after some fiddling around I have both signals being fairly consistent. I've copied my settings here in case it helps someone else.

My general findings are: trying different network modes & channels had the biggest effect. Setting the channel width to 20mhz was great for 2.4 but auto works better for 5. Specific channels had a HUGE difference, which I'm chalking up to my specific environment. I also should've left the 2.4 settings alone as it was way steadier yesterday - however signals overall seem to be lower today (thought it might be the dishwasher but it's been off for 10min now).

 

[L&LD]

Seems like you're using channel 9 for your 2.4GHz network. I would advise you change it to a primary control channel instead (1, 6 or 11).

The way you have it set now, you will see variations in performance of that band whether another AP is broadcasting on channels 6 or 11, so the potential is that you could be effectively slowed down by two AP's that do not interfere with each other (and the potential to slow your WiFi to a crawl).

Thanks - after some fiddling around I have both signals being fairly consistent. I've copied my settings here in case it helps someone else.

My general findings are: trying different network modes & channels had the biggest effect. Setting the channel width to 20mhz was great for 2.4 but auto works better for 5. Specific channels had a HUGE difference, which I'm chalking up to my specific environment. I also should've left the 2.4 settings alone as it was way steadier yesterday - however signals overall seem to be lower today (thought it might be the dishwasher but it's been off for 10min now).

View attachment 4281 View attachment 4282

 

[SunrisePro]

I thought the general recommendation was to avoid channel 6 since that's the default channel for most routers? I chose 9 based on what other signals I see: four on 6 (including the one from my Verizon router that I don't use) and one on 11.

I just tried switching channels based on your suggestions with these results:
1: major drop in signal strength
6: improvement but less than ch9
11: about the same as 9

I'll keep it at 11 & see how it goes.

 

[L&LD]

The 2.4GHz band does not overlap on channels 1, 6 and 11 (and 13 where applicable) when 20MHz channel width is utilized. If you choose a channel (like 9) which is between two main control channels, your network will interfere with your neighbors (on both the 4 ssid's on channel 6 and the one on channel 11, in your specific case) as will your neighbors utilization of their networks interfere with yours. All the time. Each and every time you or your neighbors use WiFi. Not to mention other interference sources that won't even try to adjust for other AP's.

In almost all cases, I too see channel 11 as the best channel to use for the 2.4GHz band. Even if it is the one most heavily populated by other nearby AP's too.

By using a main control channel you are syncing your AP with the fewest neighboring AP's and can then fairly share the bandwidth possible on any given channel. When you use a channel as a control channel that is interfering with AP's on different channels at the same time, the performance of the network drops significantly and consistently for all (usually at the time when everyone wants to be online too).

I thought the general recommendation was to avoid channel 6 since that's the default channel for most routers? I chose 9 based on what other signals I see: four on 6 (including the one from my Verizon router that I don't use) and one on 11.

I just tried switching channels based on your suggestions with these results:
1: major drop in signal strength
6: improvement but less than ch9
11: about the same as 9

I'll keep it at 11 & see how it goes.

 

[sfx2000]

The 2.4GHz band does not overlap on channels 1, 6 and 11 (and 13 where applicable) when 20MHz channel width is utilized. If you choose a channel (like 9) which is between two main control channels, your network will interfere with your neighbors (on both the 4 ssid's on channel 6 and the one on channel 11, in your specific case) as will your neighbors utilization of their networks interfere with yours. All the time. Each and every time you or your neighbors use WiFi. Not to mention other interference sources that won't even try to adjust for other AP's.

In almost all cases, I too see channel 11 as the best channel to use for the 2.4GHz band. Even if it is the one most heavily populated by other nearby AP's too.

There is no such thing as a control channel in 802.11... not to mince on semantics, but a control channel does mean things to those of us that have worked on Wireless WAN technologies...

I agree that 1, 6, and 11 are very good places to start - and generally, those are the preferred channels to use - 6 is a bit of a challenge, like OP mentioned, many consumer AP's default to this out of the box - I tend to like either starting with 11 (like L&LD) or 1, mainly because some folks insist on using 40MHz channels in 2.4, and when there, the primary is usually 1 or 11, with the secondary stepping pretty hard on 6 as a result (1+5 or 11-7)...

Generally though, any channel is probably good enough if you have enough RSSI above other AP's - so for OP's case, 9 might work - but I would suggest maybe 11 is better in that case.

 

[stevech]

Other WiFi routers or APs can cause CSMA/CA delays and reduction of throughput.. but only if that SSID often carries heavy traffic.

 

[SunrisePro]

Thanks, seems like the signals are nice & consistent now. I see how the Verizon router's signal fluctuates wildly, which is likely why DLNA performance was so spotty with it.

 

[System Error Message]

last time when i had inconsistent signals with a 3G usb dongle i wrapped a power cable around it that isnt connected to the mains and it helped with the signal may work for wifi routers too. Might be worth testing.

 

[L&LD]

A 'control' channel in my vocabulary is a channel that with minimum channel width will not interfere with other channels. That is why 1, 6, 11 (and 13 where applicable) are labeled as 'control channels' by me.

Any other setting will guarantee interference from more than one AP in a busy WiFi environment.

What I don't know for certain is if the time sharing / scheduling that WiFi does can do so between three channels? I have found in practical tests that this is usually no, at least that is what it seems like to me. When interference is on AP's on the same channel (all at 20MHz width) it is less of an impact than when interference is between 3 active AP's all on different channels (and the same 20MHz width each).

There is no such thing as a control channel in 802.11... not to mince on semantics, but a control channel does mean things to those of us that have worked on Wireless WAN technologies...

I agree that 1, 6, and 11 are very good places to start - and generally, those are the preferred channels to use - 6 is a bit of a challenge, like OP mentioned, many consumer AP's default to this out of the box - I tend to like either starting with 11 (like L&LD) or 1, mainly because some folks insist on using 40MHz channels in 2.4, and when there, the primary is usually 1 or 11, with the secondary stepping pretty hard on 6 as a result (1+5 or 11-7)...

Generally though, any channel is probably good enough if you have enough RSSI above other AP's - so for OP's case, 9 might work - but I would suggest maybe 11 is better in that case.

 

[SunrisePro]

Ugh - for non-signal related reasons I switched to a WRT1900ACS. The 2.4ghz signal is fluctating terribly. The best I've got is the following:

Security: WPA2 Personal
Network: G only (behaves the same as B/G mixed)
Channel: 11 ( I tried 1, 6 & 9 - 11 has the strongest signal)
Ch width: 20mhz only

Where the signal drops every minute or so instead of more frequently. 3 of the devices in the house have to use the 2.4 so I need to get this resolved somehow. If not, it's back to the drawing board for a new router...

 

[SunrisePro]

This is what is fairly steady now (no 2.4 signal drops in the last few minutes):

Security: WPA2 Personal
Network: BG only
Channel: 11
Ch width: 20mhz only

I tried switching to WPA2 mixed (it was terrible) and when I switched back to simple WPA2 the signal magically stabilized.

 

[SunrisePro]

I know the BG is an issue due to the crap wifi on a Lenovo Ideapad. I just got a usb wifi adaptor for it so we can at least bump the 2.4ghz up to N.

 

[sfx2000]

By using BG only mode you're cutting a large amount of theoretical bandwidth away. I also do agree with only using 1,6,11 as mentioned above(as you're doing now).

By putting the AP into B/G mode, it's also putting the neighboring AP's into N-Protection mode, which impacts their bandwidth...

B/G/N with 20MHz channels works best with the WRT1900acV1 in my experience...

 

[SunrisePro]

That was steadiest for me with the ACv1 as well.

Twice in the last couple of hours both 2.4 & 5Ghz networks dropped completely & came back on after a couple of minutes. The Netgear R7000 that's out for delivery can't arrive soon enough.