Question Internet stops working - switch fault?

sibuns

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Mar 11, 2014
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Hello,

I have very strange problem in my home network. So i have an ISP modem which is connected to the router. Computer is connected directly into router to port 1. From port 2 i have 10m cable that goes to another side of the room connected to a tplink 5 port switch. On the switch i have TV, AV receiver, and tv box.

The problem started a month ago... Whole internet in the house stopped working. Everything... Tv, av receiver, computer, wifi... I just thought that there was a problem with ISP so i called them and they said all is ok on their end.

Next step i restarted modem and router and the whole internet was still down.

Now here comes the strange stuff. I then disconnected switch from power and computer and wifi start to work. So the switch is causing all the problem.. i thought there was an issue with a power suppy and i change it, but the problem is still there. Its working fine for some days then suddenly stops working. I disconnect switch from power and plug back in and it is working again for some days...

The thing that bugs me is that why the whole internet dies. Why does wifi dies and why doesnt my computer have internet which is connected to router not switch. If the switch was dying on me, then the devices that are connected to the switch wouldnt have internet.

Anyone has any good answer to this problem?

Thank you and best regards
 

kanewolf

Titan
Moderator
Hello,

I have very strange problem in my home network. So i have an ISP modem which is connected to the router. Computer is connected directly into router to port 1. From port 2 i have 10m cable that goes to another side of the room connected to a tplink 5 port switch. On the switch i have TV, AV receiver, and tv box.

The problem started a month ago... Whole internet in the house stopped working. Everything... Tv, av receiver, computer, wifi... I just thought that there was a problem with ISP so i called them and they said all is ok on their end.

Next step i restarted modem and router and the whole internet was still down.

Now here comes the strange stuff. I then disconnected switch from power and computer and wifi start to work. So the switch is causing all the problem.. i thought there was an issue with a power suppy and i change it, but the problem is still there. Its working fine for some days then suddenly stops working. I disconnect switch from power and plug back in and it is working again for some days...

The thing that bugs me is that why the whole internet dies. Why does wifi dies and why doesnt my computer have internet which is connected to router not switch. If the switch was dying on me, then the devices that are connected to the switch wouldnt have internet.

Anyone has any good answer to this problem?

Thank you and best regards
Is that 10m cable a "flat" cable? If so, that would be my first thing to replace.
 

sibuns

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Yea but wouldnt only the devices which are connected to the switch lose internet connection(if the switch was bad)? Funny thing is that all devices, even that devices which are connected to the router
 
What do you mean the wifi dies. Is it that you can't even find the network or you can find the network and connect it just doesn't work.

My best guess would be you have a IP conflict.

What happens if you have the switch plugged into the router but nothing else plugged into the switch. I that works connect 1 device at a time.

A switch is pretty stupid so I can't see how it could hurt your network. That is not to say it can't happen. All you really need to do is take a cable and plug 2 ports together and your whole network will crash with many cheaper switches. This causes a loop and crash even huge corporate networks.....but those switches have features to prevent it.
 

sibuns

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Hello,

The SSID of wifi is visible but when i tried to connect i get an error (something like wan disconnected or that the router couldn't get the IP). Its hard to test because the error is so random. It can works for day... Once i get an error and when i disconnect the tv out of the switch the internet start to work again. I thought it was the TV but im not sure. I dont get it how can the whole internet stoped working if the tv is connected to switch. I would get it if all the devices conencted to switch stoped working, but not the whole network.

I dont have any loop so this is not the issue.

The switch is TP LINK TL-SG105
 
It makes it even more likely that the problem is some kind of ip conflict. A switch has no concept of IP addresses.

You are going to have to systematically test to see which device is causing this. It is much more likely it is one of the devices plugged into the switch causing this.

That switch costs about $15 so the fastest thing if you really think it is the switch is to just buy a new one. That particular switch is extremely popular and has almost no problems. Most times if you get a switch failure it just will not power on.
 

sibuns

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So what do you think it is ? You think it is an ip conflict ? So if i would set the static IPs on all my devices which are connected to the switch, the problem should be gone ? If its not gone, then the problem is with the switch itself ?

Best regards
 
That would be a good thing to try but be careful to assign static outside the dhcp scope. Doing static IP wrong can causes ip conflicts too.

It is not even a simple case of ip conflict. It almost has to be some device is trying to take the IP of the router. If it just takes another device IP then it just breaks those 2 devices.

This would have to be some kind of software bug in the device.

This is where having a fancy switch is nice. They let you intercept traffic so you can run programs like wireshark and actually see what is going on. Without that you are left to guess and find it by trial and error.
 
Another thought does the tv also have a wifi connection. Although it should not happen if the tv would connect both via wifi and ethernet and have the 2 interfaces bridged you would get the same loop as you would connecting a second ethernet cable between the router and the switch.
 

sibuns

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Hello,

No the wifi is turned of on the TV. But does the switch auto assign ip to the devices connected to switch or does it go through the router ?

Because this switch is plug and play... i dont know if you can set anything on it.
 
The switch has no concept of IP addresses at all. It only looks at the first 14 btyes of a packet that has mac addresses in it everything else is considered payload. It does not care what is in the rest of the packet...it theory you could be running some very old network protocol that does not even use IP addresses.
 

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