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

[tami]

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?

 

[tami]

I should add that I am getting 30mbps wired and 180mbps wireless sitting right next to the Google Wifi router. So it's definitely something on the wired side.

 

[ch33zw1z]

So you have a few options overall, while iperf, ping, and trace route can help find where the problem is.

1. Try a different router. I have no xp with google wifi stuff so not entirely sure what it plays like. But it might just be a little too complex for a plug n play router

2. Change the internal config. I would recommend removing the unmanaged switch for a bit and see what happens. Typically you would see the reverse, managed switch then downstream unmanaged switch.

And make sure your vlans (can't remember if you're using them) are configed correctly.

I think you see where this is going. But again, if iperf isn't reflecting the speed drops, it's probably not a LAN thing. Contact the ISP. They'll probably tell you to plug directly into the modem and test again.

 

[tami]

Yeah, the only thing that I might have a question with here is the internal config of the unmanaged switch. Only thing is that the unmanaged switch is right next to the computer, and the managed switch is on a different floor (my basement). So the logistics of setting this up are not easy.

 

[ch33zw1z]

Yeah, the only thing that I might have a question with here is the internal config of the unmanaged switch. Only thing is that the unmanaged switch is right next to the computer, and the managed switch is on a different floor (my basement). So the logistics of setting this up are not easy.

The unmanaged switch really has no internal config. Just a bunch of ieee standards it follows and basic switching functions.

Also, if you're not using any plans, just replace the managed switch with an unmanaged switch for now and see if that resolves it.

There's some stuff you can try, but you may find that it's an ISP issue. Just keep iperf, ping, and trace route handy for problem determination and isolation

 

[tami]

There's some stuff you can try, but you may find that it's an ISP issue. Just keep iperf, ping, and trace route handy for problem determination and isolation

What would make it be an ISP issue? If I removed my Google Wifi router and communicated with the modem + one machine directly to the external internet, I get the correct amount. It's when I introduce extra hardware that things start failing. I can't fathom how this would be an ISP issue... I'm still getting 200+ mbps with Google Wifi, just not with all the other devices connected to it.

 

[ch33zw1z]

What would make it be an ISP issue? If I removed my Google Wifi router and communicated with the modem + one machine directly to the external internet, I get the correct amount. It's when I introduce extra hardware that things start failing. I can't fathom how this would be an ISP issue... I'm still getting 200+ mbps with Google Wifi, just not with all the other devices connected to it.

Ok, but nothing's really been ruled out yet. Did you already mention who the ISP is and what the modem is?

 

[tami]

Ok, but nothing's really been ruled out yet. Did you already mention who the ISP is and what the modem is?

No, but I still don't understand why that would be the issue. I have an Arris TM1602A modem (it's mine, not the ISP's), and I'm on Optimum online. But I am trying to understand where you think it might be on their end - what should I be looking at?

 

[ch33zw1z]

No, but I still don't understand why that would be the issue. I have an Arris TM1602A modem (it's mine, not the ISP's), and I'm on Optimum online. But I am trying to understand where you think it might be on their end - what should I be looking at?

Until you definitively prove it's not the modem or ISP, I'm just saying dont rule it out. Especially because you said the LAN speeds aren't suffering

 

[tami]

But wouldn't consistent 200mbps speeds be proof enough that it's probably BEHIND the router, not in front of it?

(Been trying to attach proof in an Imgur screen, but Imgur is down and I'm impatient, so...)

 

[ch33zw1z]

Ok, iperf tests on the LAN confirmed the speed drops? The screenshot and previous post indicated that LAN speeds were fine and WAN speeds were the problem?

 

[tami]

Ok, iperf tests on the LAN confirmed the speed drops? The screenshot and previous post indicated that LAN speeds were fine and WAN speeds were the problem?

So behind the router, everything is running at gigabit speeds (gigabit LAN). And Google Wifi to the WAN is fine, at 200mbit. But things BEHIND Google Wifi somewhere are bottlenecking to the WAN because I'm not getting 200mbps consistently.

I think I know the issue, it's probably some device in the LAN that is the issue and only affecting WAN services. I just am trying to see if there's something else here that I'm not considering and should be.

 

[ch33zw1z]

So behind the router, everything is running at gigabit speeds (gigabit LAN). And Google Wifi to the WAN is fine, at 200mbit.

What are you basing this on? Negotiated link speeds?

But things BEHIND Google Wifi somewhere are bottlenecking to the WAN because I'm not getting 200mbps consistently.

Ok, that's where tools like ping, traceroute, and iperf come in....to help determine what is actually impacted.

Where I was trying to point you with iperf was:

1. Problem presents itself
2. Iperf tests to (W)LAN reflect problem: Y/N
3. If 2 is Y, look at internal config: iperf and ping will help narrow it down
4. If 2 is N, look to external config, which ping and trace route can help with
- Run constant pings and trace routes to popular ip's like 8.8.8.8 or 8.8.4.4 (google dns's) and see where problem is.

I think I know the issue, it's probably some device in the LAN that is the issue and only affecting WAN services. I just am trying to see if there's something else here that I'm not considering and should be.

Sure, I understand. I don't rule anything out until I can prove it. Sometimes, connecting directly to the modem is the only way, but many times the tools can help show the problem without having to do that.

 

[tami]

What are you basing this on? Negotiated link speeds?

Behind the LAN, I'm using iperf. To connect to the WAN, I'm using fast.com and other speedtest tools.

I don't see any impact internally using iperf.

I'm on OpenDNS, not Google, but I'm still not sure how to troubleshoot this...

 

[ch33zw1z]

Behind the LAN, I'm using iperf. To connect to the WAN, I'm using fast.com and other speedtest tools.

I don't see any impact internally using iperf.

I'm on OpenDNS, not Google, but I'm still not sure how to troubleshoot this...

So here's the thing, if you're not seeing any speed drops internally, then you start looking at the WAN, which would be ISP/modem/router.

Doesn't matter which external IP you use, opendns, google dns, whatever, just as long as it's a popular one that will return pings and traceroutes consistently.

 

[tami]

So here's the thing, if you're not seeing any speed drops internally, then you start looking at the WAN, which would be ISP/modem/router.

Doesn't matter which external IP you use, opendns, google dns, whatever, just as long as it's a popular one that will return pings and traceroutes consistently.

But what if I could only test one device behind the router and get 200mbps consistently....and then I add another switch, another device, etc. and start getting less than 200mbps. Then wouldn't it be something BEHIND router, and not the modem/ISP/router?

 

[ch33zw1z]

But what if I could only test one device behind the router and get 200mbps consistently....and then I add another switch, another device, etc. and start getting less than 200mbps. Then wouldn't it be something BEHIND router, and not the modem/ISP/router?

Sure, it could, and LAN testing would confirm it. That's the "fun" part. Which links are having the problem, and which aren't? With an unmanaged switch, it's unlikely a single port is causing a problem, and you already swapped it so the new one probably isn't causing it.

You're gonna have to do what you're dreading. Pick a day to do PD, and break it down to one thing at a time. It may be a device flooding the network with broadcast, or a single cable, or your router being overwhelmed....etc...

Just keep ping, traceroute, and iperf in mind, they'll help.

Keep notes, everytime you change something, test again(both lan and wan) and write it down with results

If you're not seeing the problem locally, start to engage the ISP.

Sometimes, unfortunately, there's just no magic answer with soho gear and weird problems, it's trial and error.

 

[tami]

Fun times ahead, I guess. Thanks for taking the time to help.

 

[ch33zw1z]

Fun times ahead, I guess. Thanks for taking the time to help.

No prob, I've been in your shoes 😉 let us know how the PD goes