Verifying whether failing connectivity is due to router, modem, or ISP

ngoonee · 2016-07-10 08:42:25

So a couple of days ago I started having internet connectivity issues. Initially noticed by my wife on her android phone, but all our devices are now experiencing the same thing.

Connectivity is intermittent, and when it drops attempts to load new pages in any browser just 'hang' rather than returning an error/no connection page.

Wifi connectivity seems consistent, at least there's no error logs under systemd (I use netctl-auto).

When connection is dropped, I'm also unable to access the router login/admin pages at 192.168.0.1, and my ssh connections to my raspberry pi (also connected via wifi) get timed out. Pings just don't get through.

That last symptom suggests (to me) that the problem is with my router. It's provided by my ISP, and is almost 3 years old. How do I verify that its the source of problems, and rule out the modem or ISP-side issues?

madpierre · 2016-07-10 08:58:44

Have you tried rebooting the router? (Power off for at least twenty seconds.)

Have you checked the router's logs?

Last edited by madpierre (2016-07-10 09:09:15)

ngoonee · 2016-07-10 14:54:56

madpierre wrote:

Have you tried rebooting the router? (Power off for at least twenty seconds.)
Have you checked the router's logs?

Yes for the reboot, multiple times. And router logs are clean, literally nothing shows on the logs.

madpierre · 2016-07-10 17:28:43

ngoonee writes:
...the problem is with my router....

Agreed. Have you contacted your ISP's tech support?

Afterthought: Make sure that nothing that will interfere with radio transmission has been placed near the router or in the signal path. Also, if you've moved the router, the new location may be a problem.

Last edited by madpierre (2016-07-10 18:12:22)

Awebb · 2016-07-10 17:54:39

If you cannot connect to a machine or service in your LAN, it's probably an issue with the router. The router is responsible for all LAN DHCP and traffic management. If the modem is external, then not having a working internet connection should not affect your local network at all. Please describe your setup (incl. cables) from the outlet in the wall over your modem and your router to at least one client in the local network.

madpierre · 2016-07-10 18:33:51

Awebb writes:
If the modem is external, then not having a working internet connection should not affect your local network at all.

Indeed, one would think this to be the case. However, I've experienced similar problems in the past- connections active but no internet carrier. I couldn't access the (external) router's admin panel even with a valid hard wire connection. However, the one difference is that all devices showed a loss of internet connectivity. ISP making changes/upgrades upstream? Notwithstanding, your suggestion is certainly worthwhile.

Last edited by madpierre (2016-07-10 18:36:23)

ewaller · 2016-07-10 18:43:18

ngoonee,

Always good to hear from you Have you checked your routes to see if they are sane?
Also, any chance this could be an IPv6 problem?
Are you even getting an IPv4 address? I think you are as it is not complaining about the network not being reachable.

ngoonee · 2016-07-11 01:35:08

The setup is fairly simple and has not physically been moved for 3 years, nor have any large objects been placed differently or in obstruction.

My fibre cable comes directly to the house through some small holes in the wall to my modem, which sits on my piano, the wifi router directly above it and connected by a LAN cable. Everything else just connects to the wifi router.

I've discarded routing problems as multiple devices (my Arch laptop, my Raspberry Pi 3 running Arch ARM, 3 Android smartphones, and my wife's windows laptop) all experience connectivity problems at the same time.

I'm trying to troubleshoot on my side before going to my ISP support as the level of support here is abysmal. Beyond the normal "is it plugged in" (which I don't mind, I understand why they have to ask those questions first) support just sends a tech to the house and charges you for it. I'm probably more familiar with networking than any of the techs I've seen sent, unfortunately, which isn't saying much.

Oh, all the important devices (that is, besides the smartphones) have static ipv4 addresses assigned via the router.

EDIT: Additional data point, today as all inhabitants of the house are out to work the only connected device is the Raspberry Pi. I'm ssh-ed in, and have only experienced one disconnect since this morning (it's 2pm currently here now). This leads me to suspect router overheating with multiple devices. Unfortunately I can't think of a better way to test that then to re-add devices one by one a day at a time. Something my wife won't be too happy with I'm sure.

Last edited by ngoonee (2016-07-11 06:00:03)

madpierre · 2016-07-11 06:01:56

ngoonee writes:
...the level of support here is abysmal...

I feel your pain. I think that's an international standard.

ngoonee · 2016-07-11 07:18:05

madpierre wrote:

ngoonee writes:
...the level of support here is abysmal...

I feel your pain. I think that's an international standard.

Considering the relative value of my currency and the low wages on offer (as well as other problems related to STEM education etc.) I suppose it's only to be expected.

Tonight I'm going to see if I can monitor temperature levels on my router directly.

madpierre · 2016-07-11 08:00:59

ngoonee writes:
Tonight I'm going to see if I can monitor temperature levels on my router directly.

Worth a try.

Awebb · 2016-07-11 08:38:30

There is one other thing: You could try to unplug the modem from the router and cause massive LAN traffic with as many devices as you can find. If it's still giving you trouble, then it's the router.

JohnBobSmith · 2016-07-11 12:07:01

Simultaneous failure/slowdown could be an indication of low, intermittently changing, or otherwise insufficient bandwidth. Poor quality of service settings are also known to this, at least for me. With only one device (the one experiencing the least amount of problems, if possible) go ahead and run a network speed test using the internet site of your choosing. Then, can you paste the results here? This would give us the most reliable benchmark so to speak for all the bandwidth coming into the home. The next time you get these odd network drops, repeat the test with the same site. If the bandwidth is significantly different, this would pretty much nail bandwidth as being the issue. I highly suspect bandwidth to be an issue because of the hangs without errors. These errorless hangs could be a result of your ping(s) going haywire. This in turn could be caused by bandwidth issues. AFAIK, under sub-optimal network conditions, one of the only things that can happen is for latency to go up, to compensate for the lack of bandwidth.

I hope I'm making sense, and that I have my information right. Good luck!

ewaller · 2016-07-11 14:43:40

What is the WAN technology? Cable? DSL? 100 Base T? 1000 Base T?

IOW, can you replace the ISP provided router with something else?

ngoonee · 2016-07-11 19:36:04

Awebb wrote:

There is one other thing: You could try to unplug the modem from the router and cause massive LAN traffic with as many devices as you can find. If it's still giving you trouble, then it's the router.

I only have 1 LAN cable in the entire house, and majority of access is by smartphones anyway.

JohnBobSmith wrote:

Simultaneous failure/slowdown could be an indication of low, intermittently changing, or otherwise insufficient bandwidth. Poor quality of service settings are also known to this, at least for me. With only one device (the one experiencing the least amount of problems, if possible) go ahead and run a network speed test using the internet site of your choosing. Then, can you paste the results here? This would give us the most reliable benchmark so to speak for all the bandwidth coming into the home. The next time you get these odd network drops, repeat the test with the same site. If the bandwidth is significantly different, this would pretty much nail bandwidth as being the issue. I highly suspect bandwidth to be an issue because of the hangs without errors. These errorless hangs could be a result of your ping(s) going haywire. This in turn could be caused by bandwidth issues. AFAIK, under sub-optimal network conditions, one of the only things that can happen is for latency to go up, to compensate for the lack of bandwidth.
I hope I'm making sense, and that I have my information right. Good luck!

I'm on a 10 Mb/s symmetrical connection (yes, I know, 3rd-world infrastructure and all that) which has been reliable for years now. When I get network drops I can't even load speedtest sites etc.

While I appreciate your comments, I think bandwidth externally is unlikely to be the issue because the network drops coincide with ssh-hangs to my Pi which is internal to my LAN.

ewaller wrote:

What is the WAN technology? Cable? DSL? 100 Base T? 1000 Base T?
IOW, can you replace the ISP provided router with something else?

Yeah that's what I'm considering doing. A shop in my city just started selling Huawei WS880 (AC1750 wifi router) for the equivalent of 50USD, and as you would expect they're flying off the shelves. I'm going to go and pick a few up for myself and family members too.

WAN is optical fibre (sorry it wasn't clearer, I did reference that tangentially) to the modem, with the last connection being (I believe) 100 Base T to the router itself. Which is fairly moot due to both my pitiful bandwidth (10 MB/s, see above) and the internal LAN connectivity issues.

Latest update: after a day away at work the hangs are noticeably shorter in duration overnight, though still occurring. I'm leaning towards router overheating at this point. I'm about to stress test the network with my regular backup, let's see if this works.

EDIT: Started my regular backup (maxes out my Raspberry Pi's 1.5 Mb/s transfer, full wireless via the router) and the started 3 simultaneous downloads to max out my bandwidth. And poof the hangs are back. Roughly a minute each time. Interestingly enough my ssh connections survive the downtime where they didn't before.

Last edited by ngoonee (2016-07-11 19:58:44)

Awebb · 2016-07-11 21:06:59

ngoonee wrote:

Awebb wrote:
There is one other thing: You could try to unplug the modem from the router and cause massive LAN traffic with as many devices as you can find. If it's still giving you trouble, then it's the router.
I only have 1 LAN cable in the entire house, and majority of access is by smartphones anyway.

Regardless, if you want to rule out WAN as a source of trouble, unplug the modem and stress the router with LAN traffic.

EDIT: In case "LAN" confused you, I mean local traffic, no matter if it's wireless or not.

Last edited by Awebb (2016-07-11 21:07:46)

R00KIE · 2016-07-11 23:10:24

You say that everything except for the router is connected via wireless, when you are having trouble try doing a scan and see if anyone else is using the same channel. A neighbor might have installed a new router using the same channel as yours and it could be causing trouble.

That said, an obvious test is to connect something (laptop/desktop pc/RPI) to the router with a cable, at least you get wireless connectivity problems out of the way.

ngoonee wrote:

EDIT: Additional data point, today as all inhabitants of the house are out to work the only connected device is the Raspberry Pi. I'm ssh-ed in, and have only experienced one disconnect since this morning (it's 2pm currently here now). This leads me to suspect router overheating with multiple devices. Unfortunately I can't think of a better way to test that then to re-add devices one by one a day at a time. Something my wife won't be too happy with I'm sure.

I'd say that over a local network, be it wireless or wired even one disconnection is one too much, I would only tolerate that if the wireless signal is not very strong.

ngoonee · 2016-07-12 02:27:08

Hmm, I was just doing another stress test (copying my 80GB VM disks from machine to machine in various combinations at the same time) and it was running without a hitch for a good hour.

The only device which wasn't connected to my network was my wife's smartphone (her laptop was home and connected as part of the test).

Then my wife got home. Immediate stall in my transfers. How can one phone/device affect the wireless network like that?

ukhippo · 2016-07-12 11:07:17

Quite easily. Cloud syncing, app updates etc. are often limited or disabled over non-wifi connections. As soon as there's a wifi connection, the phone starts doing background cloud syncs and updates. Then there's all those apps running in the background...

R00KIE · 2016-07-12 12:24:05

ngoonee wrote:

Then my wife got home. Immediate stall in my transfers. How can one phone/device affect the wireless network like that?

That's probably due to crappy, slow wifi hardware or just a bad implementation. I have personal experience with that, at home I have one tablet that causes that, even when doing minimal data transfers, and one usb wifi card which when connected over usb 1.1 also does that.

ngoonee · 2016-07-12 15:11:22

Darn, that's not at all good news. In any case I got my new router today and am setting up AdvancedTomato on it. Hopefully isolating the offending device to the 5GHz band helps.

Arch Linux

#1 2016-07-10 08:42:25

Verifying whether failing connectivity is due to router, modem, or ISP

#2 2016-07-10 08:58:44

Re: Verifying whether failing connectivity is due to router, modem, or ISP

#3 2016-07-10 14:54:56

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#4 2016-07-10 17:28:43

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#5 2016-07-10 17:54:39

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#6 2016-07-10 18:33:51

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#7 2016-07-10 18:43:18

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#8 2016-07-11 01:35:08

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#9 2016-07-11 06:01:56

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#10 2016-07-11 07:18:05

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#11 2016-07-11 08:00:59

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#20 2016-07-12 12:24:05

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#21 2016-07-12 15:11:22

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