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Question Seeing unexplained dropped speeds in my network - any ideas?

tami

Lifer
Nov 14, 2004
11,576
3
81
I have an interesting setup and would be interested in seeing where my bottleneck might be.

I have a Nest Wifi (v2) connection behind my cable modem. Google WiFi's outbound port then goes into a GS308 Netgear unmanaged switch, which 1) connects directly to my desktop 2) has a cable that then goes to a Netgear managed switch (JGS524E) that then has cables that are wired and go out to Ethernet ports in my home as well as to various Google WiFi pucks to amplify the wireless connectivity.

I notice that every so often, my wired connection from the GS308 switch will drop from my 200mbit speed (220mbps is typically what I get) to 20-40mbps. This also impacts the wireless devices and the rest of the devices in the house. Until I either power cycle the GS308 or move the outbound Google WiFi cable to another port on the switch, it stays at that 20-40mbps speed. But whenever I move the cable, I get fast speeds again. Then they drop, which could be either within a few hours or a few days. This ends up spreading throughout my home (wired AND wireless) until I power cycle or relocate the cable again.

Thinking the issue was the GS308, since that serves both the wired computer and the entire network,. I replaced it with a GS108, and the issue happened again, so it's not the switch. I also tried another cable outbound from the Google WiFi router to the GS308 and nothing changed (again, that is the only other common denominator for the whole network).

The issue is not on the Google WiFi side, because the app says that my speed is 220mbps every day when it does its daily speed test.

To summarize the setup:
* Modem > Google WiFi > Cable (which I've replaced) > GS308 (which I've also replaced) > 1) cable to a wired computer and 2) cable to wired/wireless switch for the rest of the network - and both wired computer and home/wireless/wired network all go down.

Here's a basic network diagram simplifying: link -

I feel like besides the Google WiFi, which is not experiencing these measured speed reductions, there's nothing else to troubleshoot here. Anyone else know better than me?
 

SamirD

Golden Member
Jun 12, 2019
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I've seen oddball issues like this with unmanaged switches very rarely where it is the switch, and I'm willing to bet that is the case with you as well. Changing to another netgear switch wasn't the solution, but I believe if you put a tplink, trendnet, ie any other brand switch there, the problem will go away. :)
 
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tami

Lifer
Nov 14, 2004
11,576
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I've seen oddball issues like this with unmanaged switches very rarely where it is the switch, and I'm willing to bet that is the case with you as well. Changing to another netgear switch wasn't the solution, but I believe if you put a tplink, trendnet, ie any other brand switch there, the problem will go away. :)
Interesting - why do you think this is? So Netgear doesn't play well with Netgear?! Thanks Samir!
 

ch33zw1z

Lifer
Nov 4, 2004
34,324
13,240
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Yes, but then it drops to 20mbps...
Ok, so youre running speedtests outside of your network.

Use iperf3 to test speeds inside the network. You will need two devices, like windows or linux devices. You test the link from one to the other, it's useful to see if your internal network is the problem, and if so where it is.
 
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tami

Lifer
Nov 14, 2004
11,576
3
81
Ok, so youre running speedtests outside of your network.

Use iperf3 to test speeds inside the network. You will need two devices, like windows or linux devices. You test the link from one to the other, it's useful to see if your internal network is the problem, and if so where it is.
Thanks - I'll take a look at this if the Trendnet switch I am now using causes an issue. I do have a Linux server I can test with and an FTP server.

but right now, regardless of where the speed is dropping, the speed drops are resolved when I power cycle the switch or move the cable from one port to another. So what would be the cause of that?.
 

VirtualLarry

No Lifer
Aug 25, 2001
52,272
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but right now, regardless of where the speed is dropping, the speed drops are resolved when I power cycle the switch or move the cable from one port to another. So what would be the cause of that?.
Are the Google wifi "pucks" mesh? I wonder if you've got a loop somewhere in your network causing a broadcast storm.
 
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ch33zw1z

Lifer
Nov 4, 2004
34,324
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Thanks - I'll take a look at this if the Trendnet switch I am now using causes an issue. I do have a Linux server I can test with and an FTP server.

but right now, regardless of where the speed is dropping, the speed drops are resolved when I power cycle the switch or move the cable from one port to another. So what would be the cause of that?.
May wanna get familiar with iperf while the network is working.

I would also consider putting the managed switch first in line. Are you using any vlans?

Question about the diagram, how are you running wifi clients behind the managed switch?
 
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tami

Lifer
Nov 14, 2004
11,576
3
81
Are the Google wifi "pucks" mesh? I wonder if you've got a loop somewhere in your network causing a broadcast storm.
Yeah, that's what I'm wondering too, and that'd affect my wired connection, right?

May wanna get familiar with iperf while the network is working.

I would also consider putting the managed switch first in line. Are you using any vlans?

Question about the diagram, how are you running wifi clients behind the managed switch?
They're mesh pucks. No vlans.

So far the Trendnet thing seems to be working, but I'm wondering if it was really that easy. Sometimes these "broadcast storms," if that's what they are, are happening with only a few wifi devices (cameras) and two computers running on the network.
 

ch33zw1z

Lifer
Nov 4, 2004
34,324
13,240
146
Yeah, that's what I'm wondering too, and that'd affect my wired connection, right?



They're mesh pucks. No vlans.

So far the Trendnet thing seems to be working, but I'm wondering if it was really that easy. Sometimes these "broadcast storms," if that's what they are, are happening with only a few wifi devices (cameras) and two computers running on the network.
Broadcast storms happen when there's multiple paths between endpoints on the LAN(including WLAN). That's why I asked about the diagram saying there's wifi devices behind the managed switch. Are those pucks hardwired to the managed switch?
 

tami

Lifer
Nov 14, 2004
11,576
3
81
Broadcast storms happen when there's multiple paths between endpoints on the LAN(including WLAN). That's why I asked about the diagram saying there's wifi devices behind the managed switch. Are those pucks hardwired to the managed switch?
3 are, 3 aren't.
 

ch33zw1z

Lifer
Nov 4, 2004
34,324
13,240
146
Ok, if you keep having the problem, you may wanna review the config and, if possible, see if unplugging those resolves it.
 

tami

Lifer
Nov 14, 2004
11,576
3
81
Yeah, thanks. It may be a Netgear managed switch <> Netgear unmanaged switch conflict as suggested by @SamirD, as it works better now. Very weird that going to a TrendNet unmanaged switch in lieu of my Netgear unmanaged switch was the solution, but that was an easier fix over reconfiguring my pucks (which I already reduced from 10 to 6 thanks to incredible old-architecture interference in my home). Thank you @ch33zw1z!!
 

ch33zw1z

Lifer
Nov 4, 2004
34,324
13,240
146
Glad it's working so far. I still recommend getting familiar with iperf3. It's a great tool to test links. I always use it after changing something to verify the new stuff works well, or at least as designed 😉
 
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tami

Lifer
Nov 14, 2004
11,576
3
81
Ok, so youre running speedtests outside of your network.

Use iperf3 to test speeds inside the network. You will need two devices, like windows or linux devices. You test the link from one to the other, it's useful to see if your internal network is the problem, and if so where it is.
All right @ch33zw1z you're up - what's the desired syntax I should use for iperf3? 🙃 Will see if I can figure out what's going on here....

When you say two devices, I have a few dozen devices connected to my home network. Should I be doing this everywhere or...? Any tips on how to troubleshoot this effectively?

thanks!
 

ch33zw1z

Lifer
Nov 4, 2004
34,324
13,240
146
So did the problem return?

I'm out and about right now, I can do a better tutorial later when at home
 

tami

Lifer
Nov 14, 2004
11,576
3
81
So did the problem return?

I'm out and about right now, I can do a better tutorial later when at home
I'm not 100% sure it returned. The situation now is different. Whole network is getting 20-60mbps outside the wifi router.

No rush - thank you.
 

ch33zw1z

Lifer
Nov 4, 2004
34,324
13,240
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Ok, so to test a link between devices, you need to set one as the server and then point a client at it. You need to know what IP the server is...

On the "server", which is whatever device you want it to be, open a command prompt to where the iperf3.exe is located, then type "iperf3 -s" but without the quotes...

Then on the "client" device, you would type "iperf3 -c ip_of_server"

Here's two screen snips, I ran iperf3 on a raspberry pi running ubuntu as the server, and pointed my windows desktop at it. This only goes thru one switch, but I can use this same process to test whatever paths I want. I test wireless speeds from some laptops using this stuff as well. You can potentially find where a bottleneck is, and this does not test outside the network (unless you configure other things to test outside the network). but for your purposes, see if local speeds aren't impacted and if they are, where they're at. I recommend keeping a log as well, as detailed as pertinent.

Edit: you may get some firewall pop ups in windows the first time you run iperf3, just allow it obviously. In linux, it might just time out unless you allow it there as well. For ubuntu it's just sudo ufw allow iperf3

Edit 2: if you're running any of this in linux, you don't need to browse to the directory, just run iperf3 and linux is smart enough to know what to do.
 

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tami

Lifer
Nov 14, 2004
11,576
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@ch33zw1z thanks - I'm getting 1gbit at home as expected, so I think the issue is on the greater network... thing is, Google WiFi reports I am getting 200mbit. Everything local looks safe.

How would you suggest I troubleshoot this further?

My main machine to my Linux box (my Windows server to my Linux box was the same - to each other as well).
Code:
# iperf3 -s
-----------------------------------------------------------
Server listening on 5201
-----------------------------------------------------------
Accepted connection from 10.10.10.100, port 64910
[  5] local 10.10.10.10 port 5201 connected to 10.10.10.100 port 64911
[ ID] Interval           Transfer     Bandwidth
[  5]   0.00-1.00   sec  82.6 MBytes   692 Mbits/sec                 
[  5]   1.00-2.00   sec  94.9 MBytes   796 Mbits/sec                 
[  5]   2.00-3.00   sec   104 MBytes   870 Mbits/sec                 
[  5]   3.00-4.00   sec   104 MBytes   871 Mbits/sec                 
[  5]   4.00-5.00   sec   105 MBytes   879 Mbits/sec                 
[  5]   5.00-6.00   sec   108 MBytes   909 Mbits/sec                 
[  5]   6.00-7.00   sec  82.7 MBytes   695 Mbits/sec                 
[  5]   7.00-8.00   sec   109 MBytes   916 Mbits/sec                 
[  5]   8.00-9.00   sec  97.6 MBytes   819 Mbits/sec                 
[  5]   9.00-10.00  sec   103 MBytes   867 Mbits/sec                 
[  5]  10.00-10.04  sec  4.19 MBytes   940 Mbits/sec                 
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth
[  5]   0.00-10.04  sec  0.00 Bytes  0.00 bits/sec                  sender
[  5]   0.00-10.04  sec   995 MBytes   832 Mbits/sec                  receiver
-----------------------------------------------------------
Server listening on 5201
-----------------------------------------------------------
So to me, my Google wifi says the network is at 200 mbps. But everything BEHIND Google Wifi doesn't. Where do we go from here?
 

ch33zw1z

Lifer
Nov 4, 2004
34,324
13,240
146
So if I understand you correctly, 200mbps is your WAN speed from the ISP, and it's ok for now. And the LAN tests are working as expected?

Have to test paths throughout the config? Such as links on the managed switch, and links between switches, etc...

Are you still experiencing the problem?
 

tami

Lifer
Nov 14, 2004
11,576
3
81
So if I understand you correctly, 200mbps is your WAN speed from the ISP, and it's ok for now. And the LAN tests are working as expected?
Not exactly. The Google Wifi hub says it's 200mbps. But devices connected to the Google Wifi hub are not getting 200mbps. They're getting 20mbps. So the issue I initially reported is still there. For awhile, I get 200mbps. Then it precipitously drops and never recovers.

I think the safest way to test this is to remove all devices... the switches to me might be causing a bottleneck.
 

ch33zw1z

Lifer
Nov 4, 2004
34,324
13,240
146
Not exactly. The Google Wifi hub says it's 200mbps. But devices connected to the Google Wifi hub are not getting 200mbps. They're getting 20mbps. So the issue I initially reported is still there. For awhile, I get 200mbps. Then it precipitously drops and never recovers.

I think the safest way to test this is to remove all devices... the switches to me might be causing a bottleneck.
Ok, so when the problem appears, does iperf confirm the speed drop?
 

aigomorla

Cases and Cooling Mod PC Gaming Mod Elite Member
Super Moderator
Sep 28, 2005
19,253
1,628
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If your complaining about your internet speed:

I would inspect modem.
Also possibility that the modem might be overheating, and throttling.

It may not be on your end but the ISP end.
Possibly it could also be throttling your neighborhood at set hours as a overhead during major congestion.
If you have spectrum, i would probably start point fingers at them first.
 

tami

Lifer
Nov 14, 2004
11,576
3
81
Ok, so when the problem appears, does iperf confirm the speed drop?
Until you last asked, I was running iperf only internally (on devices behind the router, not to the public network). My internal speed has never been an issue; it's only been external speeds.

That said, going out to the public network: it's not good and supports what fast.com is telling me. I'm not sure what value iperf is adding since it's basically fast.com on CLI for the internal speed - which I guess is what you said earlier, but I hadn't had any concerns about my internal speeds, it's outbound connectivity that I'm worried about.

Code:
Connecting to host x.x.x.x, port 5201
[  4] local 10.10.10.100 port 52931 connected to x.x.x.x port 5201
[ ID] Interval           Transfer     Bandwidth
[  4]   0.00-1.00   sec  1.50 MBytes  12.6 Mbits/sec
[  4]   1.00-2.01   sec  2.00 MBytes  16.7 Mbits/sec
[  4]   2.01-3.00   sec  2.12 MBytes  17.9 Mbits/sec
[  4]   3.00-4.01   sec  1.88 MBytes  15.6 Mbits/sec
[  4]   4.01-5.00   sec  1.00 MBytes  8.50 Mbits/sec
[  4]   5.00-6.01   sec   640 KBytes  5.19 Mbits/sec
[  4]   6.01-7.00   sec   768 KBytes  6.34 Mbits/sec
[  4]   7.00-8.01   sec   384 KBytes  3.13 Mbits/sec
[  4]   8.01-9.00   sec   384 KBytes  3.15 Mbits/sec
[  4]   9.00-10.01  sec   384 KBytes  3.13 Mbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth
[  4]   0.00-10.01  sec  11.0 MBytes  9.22 Mbits/sec                  sender
[  4]   0.00-10.01  sec  10.8 MBytes  9.06 Mbits/sec                  receiver
If your complaining about your internet speed:

I would inspect modem.
Also possibility that the modem might be overheating, and throttling.

It may not be on your end but the ISP end.
Possibly it could also be throttling your neighborhood at set hours as a overhead during major congestion.
If you have spectrum, i would probably start point fingers at them first.
Thanks - let me clarify my earlier setup from the very first post:
"* Modem > Google WiFi > Cable (which I've replaced) > GS308 (which I've also replaced) > 1) cable to a wired computer and 2) cable to wired/wireless switch for the rest of the network - and both wired computer and home/wireless/wired network all go down. "

I've added bold to where the 200mbps connection is stable. So according to my Google Wifi, I'm getting 200mbps. However, I don't actually see it; only the router does (per Google Wifi's daily speedtest screenshot). FWIW, I now have a TEG-S82G replacing the GS308, but both switches hit 20mbps eventually (the GS308 was faster at diminishing my speed and it took 4-5 days to get 20mbps on the TEG-S82G whereas it took like 30 minutes on the GS308).

Something somewhere between Google Wifi and the rest of the network is causing a significant bottleneck on my speeds. I realize I have two switches, but even if there's a loop somewhere, wouldn't I eventually get 200mbps again and it wouldn't be a consistent 20mbps?

I could of course start troubleshooting by removing every single device on my network but I have more than 45 devices connected to the network... the router/switch setup can't easily be switched out.
 

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