Advice needed - problem with network at work

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bluepoole

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I hope the boffins could give me advice on the problem we have at work, with our network.

We have a Telkom ADSL line, which goes into a Telkom DLINK router. Plugged into the router, is a LAN cable going to a switch, and then all PC's (five in total) are connected to the switch.

Everything worked fine, until one given day, then we started having problems. What would happen is that one or two PC's will just drop off the network (yellow exclamation mark shown in the taskbar), and then we struggle to get them back on the network.

We are a very small company, four employees in total, so we don't have an IT guy or anything - and we are not too clued up on IT and networks - so any help would be appreciated.

What could be the cause, and where could one start to look for the problem?
 
Step 1 would be to check the IPs of all the workstations. It could be that there are conflicting IPs, causing the connectivity to drop.
1000s more reasons for this, but that would probably be step 1.

Have you tried simply unplugging and plugging the network cable on those machines?



**Check for IP
Click on the Start button (bottom left)
type "cmd" - Hit Enter
type "ipconfig" - Hit enter

There should be a "Ethernet adapter Local Area Connection" with an IPv4 Address similar with format xx.xx.xx.xx / 10.0.0.0 / etc...
 
Last edited:
I would simply test with another Router to see if the problem goes away.

If it was one machine only then you would look at the machine, more than one machine says it's the "provider" to that machine that is problematic.

Are they all wired or is there a Wireless Access Point in the middle somewhere?
 
Jip, I did check the IP addresses this morning and there doesn't seem to be any conflicts - we have unplugged and plugged in the cables on all PC's, we have reset the router, etc.

I checked the TCP/IP properties of the network adapters on all PC's and the IP address seem to get assigned dynamically.

All of a sudden all the PC's will be online and working again, then a few hours later one will drop off again. Also, sometimes the connection will drop on a PC for a few seconds, and then come back on.
 
SauRoNZA said:
I would simply test with another Router to see if the problem goes away.

If it was one machine only then you would look at the machine, more than one machine says it's the "provider" to that machine that is problematic.

Are they all wired or is there a Wireless Access Point in the middle somewhere?
Click to expand...

They are all wired.

Could it be a faulty router?
 
Restart the entire infrastructure. Also plug everything into other open ports...If there is a particular PC that keeps giving issues, plug that pc into another port, see if it goes away. Plug something else into that port and see if it also gives issues? But I agree with bluepoole, it could be faulty equipment. Lots of lightning over the last few weeks.
 
i have found that some Apple devices dont tell the DHCP server which IP they are using, causing IP conflicts. i dont know if it applies to you but worth a mention.

All the computers on the network are configured correctly and a phone or ipad causes problems when it connects wirelessly.

start your DHCP pool from 100 and up or something, configure all your office devices staticly below 100.


oh and some wireless printers cause this to happen too.
 
access said:
i have found that some Apple devices dont tell the DHCP server which IP they are using, causing IP conflicts. i dont know if it applies to you but worth a mention.

All the computers on the network are configured correctly and a phone or ipad causes problems when it connects wirelessly.

start your DHCP pool from 100 and up or something, configure all your office devices staticly below 100.


oh and some wireless printers cause this to happen too.
Click to expand...

Very interesting - we will look into this, since we do have 3 x Apple devices connected to the router via WiFi.
 
What switch is it? If its managed have you checked the logs form it? Also worth checking the logs for all other network devices.
 
This is the switch in question - the router itself is a Telkom DLINK though

switch.jpg
 
My colleague's PC just went offline again...it worked fine for two hours now. Sometimes he disables the network adapter and enables it again, then it works fine for a while. It doesn't always help though.

Sounds to me like it is either the switch or the router that might be the culprit? As mentioned, the switch is new though.
 
What happens on two PC's now - Windows shows the PC as being connected, but when you try to load a website, you get the following error:

DNS_PROBE_FINISHED_NO_INTERNET
 
bluepoole said:
My colleague's PC just went offline again...it worked fine for two hours now. Sometimes he disables the network adapter and enables it again, then it works fine for a while. It doesn't always help though.

Sounds to me like it is either the switch or the router that might be the culprit? As mentioned, the switch is new though.
Click to expand...

Might be an issue with routing? I had an issue where I had a radio on the roof (pointing to WISP) and a router providing connectivity in the house.. Then, at times, a device will connect to the router, instead of going via the router to the radio, and thereby "lose" connection.

So just check the routing protocols on your switch, if it is only the ethernet clients affected.
 
We have now plugged one of the problematic PC's directly into the router (bypassing the switch) and problem still persists...
 
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