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Nightmare IP Conflict on Small 13-15 Device Network


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#1 Bringo

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Posted 14 March 2016 - 10:21 PM

OK so I have been dealing with this issue for over a month. Here are the basics. 

 

Small business network on Dedicated DSL from a small local ISP. Internet connection comes in from Modem then into Netgear WNDR4500 Router. WAN IP is 192.83.""."" subnet specified by the ISP, which I did not get to choose. LAN Subnet is 192.168.1."" . There is no domain or workgroup in place.

Netgear Router passes DHCP to all network clients and is the only DHCP source. There are only ever 15 devices MAXIMUM connected to this network, and only 4 of them are actual PCs( All Windows 7 Home Premium) with the rest being printers, iPads, cell phones, etc. 

 

Hardline ethernet goes from Router Port 1 into a Netgear Gigabit Switch, which then feeds into the patch panel supplying internet to the 5 CAT5e network drops in the office.

 

All devices on the network operate perfectly fine without issue except for the Company owner's PC(figures) which is a desktop PC that never moves and is fed from the CAT5e network drop in his office. 

 

His PC, multiple times per day warns him of an IP address conflict on the network, however he never loses internet connectivity and there is never an actual conflict. I have logged into the Router within 30 seconds of the IP Conflict message becoming present on his PC and there is no IP conflict to be found. DHCP is functioning and all devices show properly in the router list with their own individual IP addresses. Upon checking the Event logs on his PC, the TCP/IP errors are present and show an IP conflict, but instead of providing a MAC address or IP address that is conflicting, the logs show "" in place of what would normally be the MAC address and IP address in question. Like I said, there is no loss of internet connectivity at any point, he just gets the conflict pop up. I have given him an IP Config batch file to run from his desktop just as a pacifier although it really is doing nothing but releasing and reclaiming an IP and flushing his DNS cache. It solves nothing except keeping him temporarily quiet because he thinks it looks cool when the command prompt shows up and he feels tech(y).

 

DHCP range is 192.168.1.100 - 192.168.1.253. Default gateway is 192.168.1.1. Only 192.168.1.100 - 192.168.1.115 are ever claimed via DHCP due to the small amout of devices. I've tried setting him aside a reserved static IP outside as well as inside of the DHCP range, but not at the same time of course, They were set statically in his network adapter as well as reserved in the router by IP and MAC address. Again, internet connection good the whole time throughout all of these configuration changes but still, everyday he gets the conflict message. I have disabled all other network adapters within his PC as well to ensure it is not a secondary adapter causing this problem. Router firmware is up to date as well as all of the drivers on his PC.

I feel I have pretty much exhausted the options that I can think of off the top of my head at this point. Like I said, no other machine or device on the network has or has ever had this issue, it's just the one PC.

 

If anyone has any magic lined up, I'd love to give it a shot. The part that really has me stumped is that everything works perfectly fine except for this seemingly false flag warning. As is always the case, I cannot just ignore this as it signals to the owner that his network has issues, which I suppose it does, at least somewhere anyway. 


Edited by hamluis, 15 March 2016 - 12:00 PM.
Moved from Win 7 to Networking - Hamluis.


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#2 WebWalker67

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Posted 15 March 2016 - 04:39 AM

You can have 4 pc (LAN cable connected) to fixed/static ip start from 192.168.1.50 to 54.

 

Those 4 pc(s) will never IP conflict with those wireless devices started from 192.168.1.100 to 253



#3 Wand3r3r

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Posted 15 March 2016 - 07:33 PM

"They were set statically in his network adapter as well as reserved in the router by IP and MAC address"

 

Do one or the other but not both = good practices.

 

Does this pc have multiple Ethernet ports or Ethernet and wifi?

When he gets the ip conflict message have you tried pinging that pc by host name?

Does it resolve to the correct ip address when you do so?

You have a ip plan documented that shows everything that is statically and dynamically assigned?



#4 Bringo

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Posted 16 March 2016 - 05:28 PM

 

 

Do one or the other but not both = good practices

 

I agree, however he does still get the conflict whether only one method is used or both so I am confident this is not the source of the issue.

 


Does this pc have multiple Ethernet ports or Ethernet and wifi?

 

 

PC has single ethernet port and no WiFi Adapter. 


 

When he gets the ip conflict message have you tried pinging that pc by host name?

 

 

Yes, have tried pinging by Host name and it does respond


 

Does it resolve to the correct ip address when you do so?

 

 

Yes it also does resolve to the correct IP address.


 

You have a ip plan documented that shows everything that is statically and dynamically assigned?

 

 

Everything else on the network uses DHCP to get it's IP, there is no formal IP Plan slated for this network as I get paid on a per call basis by them and they do not allow me to do any unscheduled maintenance. I usually get to work on their network for about 4 hours per month. I've spent quite a bit of unpaid time remoted into the network trying to figure this out. Like I said, I've even tried assigning the PC an IP outside of the DHCP range which it uses with no trouble other than the fact that his PC warns of the conflict still. There is no possible way the router could be passing IPs outside of the DHCP range to a different device.

 

I am wondering if he is putting his PC to sleep then when he wakes it back up the PC still has the IP which it is then trying to claim again from the router again. Still would not explain why it happens through out the day, but not much about this issue makes sense anymore.


Edited by Bringo, 16 March 2016 - 05:38 PM.


#5 Bringo

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Posted 16 March 2016 - 05:31 PM

You can have 4 pc (LAN cable connected) to fixed/static ip start from 192.168.1.50 to 54.

 

Those 4 pc(s) will never IP conflict with those wireless devices started from 192.168.1.100 to 253

This is exactly what i thought. I did in fact try this a while back assigning each of the PCs their own static outside of the DHCP range and then letting the wireless devices use DHCP. However, no luck using this method. Like I mentioned previously, no other PC on the network ever receives a conflict warning except for his regardless of the network config. I am starting to wonder if I might save myself some time and headache by just reloading his PC with a fresh Win7 install. My best guess is that this is something within Windows running rampant in an improper manner.

 

Thank you for the suggestion either way. I am sure that would solve this issue 99 times out of 100.



#6 Wand3r3r

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Posted 16 March 2016 - 05:44 PM

Look for virtual software on his pc.  A misconfigured virtual nic maybe the issue.



#7 Kilroy

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Posted 18 March 2016 - 01:53 PM

Have you tried giving his machine a different IP via DHCP reservation?  If the problem moves it is the machine, if it doesn't move there is another device out there some where.



#8 Bringo

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Posted 18 March 2016 - 02:01 PM

Have you tried giving his machine a different IP via DHCP reservation?  If the problem moves it is the machine, if it doesn't move there is another device out there some where.

 

 

 

I've tried setting him aside a reserved static IP outside as well as inside of the DHCP range, but not at the same time of course


#9 Kilroy

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Posted 18 March 2016 - 02:52 PM

Then you're looking at an issue with his machine.






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