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Laptop - Desktop - IP addressing issue

pj2014
Grafter
Posts: 103
Registered: 22-11-2013

Laptop - Desktop - IP addressing issue

Hi everyone!
Hoping someone can help with an annoying issue I have been faced with....  I'll try and be brief!
Have pc's, laptops, mobiles. tablets, sky boxes that connect/disconnect all day long, get assigned/re-assigned IP addresses and experience no problem what so ever. (router is a netgear dgn3500)
I have a particular HP DC____  micro tower (intel 2.2 or 2.4 dual core) and a Toshiba tecra m5 laptop (1.6/1.8 Intel core2 duo). When ever the HP is connected and I turn the Toshiba laptop on, the HP loses its IP address and get the yellow triangle on the network icon in the corner. I have tried repairing the connection, assigning fixed IP addresses to both devices but nothing seems to work.
I have 'retired' both machines so to speak, the HP has been replaced with a home built pc and the Toshiba laptop has been replaced with an Acer laptop and now I have no issues. But just for my own sanity was wondering if anyone encountered any such issues and how you resolved it?
I am probably going to sell both the offending computers on but do not want to should they be faulty. They both work on their own and with other networked devices but just not when both are on at the same time on my network. I have used the laptop at a family members house/network and it didn't cause any issues there (but I wasn't able to take the HP desktop to check them both at another address)
any idea's?
cheers!
pj2014
35 REPLIES
Community Veteran
Posts: 3,826
Thanks: 44
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Registered: 24-09-2008

Re: Laptop - Desktop - IP addressing issue

Are you using DHCP or static IP addressing. Hard wired or wifi connected?
I've' had a similar problem with an Ethernet port on a switch 'broadcasting continually', blocked out any other device trying to connect.
nanotm
Pro
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Registered: 11-02-2013

Re: Laptop - Desktop - IP addressing issue

yes,
for me the problem was a pc with built in gbe port(built in 02) had the identical mac address to a laptop's built in wifi card (built in 09), I fixed the problem by changing the mac address on the pc (not all motherboards support this feature), its possible that older kit from different manufacturers has a similar problem, certainly I had a mobile that had the same mac address as a printer (again different manufacturers) both devices were probably made 8 years apart and I just got a new printer to fix the issue.....
IIRC mac addresses allocations are made to each company on request (unique company indicator) in the first 4 digits and the remainder is assigned from the address table by the company concerned, but before global assignments were standardised companies just produced and imprinted addresses for each device off their own table and so conflicts were much more frequent an occurrence, although the problem was believed to be mitigated by volume dispersion (selling the duplicates in different regions)
another indication of how fast the 48bit address system is being used would be that the mac address list is being recycled so frequently even within individual companies product range
just because your paranoid doesn't mean they aren't out to get you
pj2014
Grafter
Posts: 103
Registered: 22-11-2013

Re: Laptop - Desktop - IP addressing issue

@journeys
DHCP. Combination of hard wired and wifi. (All devices)
But on these two the toshiba laptop by wifi and the HP micro tower hard wired (via home plugs)
@nanotm
I hadn't thought of duplicate mac addresses.  HP tower works fine - then power up toshiba laptop - HP loses IP address but toshiba laptop continues to work fine....  - close lid on the toshiba and the HP Micro tower re acquires an IP address..
It was all rather strange......  I will go and check the MAC addresses (I'm sure I did that, as I recall downloading a MAC modifying program)
Now I have the home built pc instead of the HP tower let me just power up the toshiba so see what happens.....
cheers

pj2014
Grafter
Posts: 103
Registered: 22-11-2013

Re: Laptop - Desktop - IP addressing issue

Unbelievable!
Ok, so I powered up the Toshiba laptop... and even with the new home built pc I have the same problem. This is bizarre.
The home built pc behaves in the same way (as the old HP desktop) and loses its IP address (yellow triangle on the network icon) the moment the Toshiba laptop connects.
I checked the MAC addresses and they are different.
I'm stumped.
nanotm
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Registered: 11-02-2013

Re: Laptop - Desktop - IP addressing issue

the pc is wired and the laptop on wifi ?
what router are you using ?
just because your paranoid doesn't mean they aren't out to get you
Community Veteran
Posts: 3,826
Thanks: 44
Fixes: 1
Registered: 24-09-2008

Re: Laptop - Desktop - IP addressing issue

another question, is the firmware up to date on the router?
Can I suggest you set the IP address in both the laptop and pc to static (say 98 & 99) then set your DHCP server (possibly you router) to exclude 98 and 99.
PeeGee
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Re: Laptop - Desktop - IP addressing issue

Quote from: pj2014
The home built pc behaves in the same way (as the old HP desktop) and loses its IP address (yellow triangle on the network icon) the moment the Toshiba laptop connects.

So the connection is lost and you say the HP/new PC loses the IP address, but is that just from the "yellow triangle" or have you checked via "ipconfig /all" ? Do the two systems actually get the same IP address ("ipconfig /all" again!).
What exactly is the connection set up for the two devices? I have seen a something slightly similar before (but whereHuh? ), which was traced to the use of a "network sharing" device that relied on the network interface powering down completely to automatically switch between PCs - but it doesn't fit your description of the problem.
Also, if cabled, have you tried moving the connections around and/or different cables - just a long shot Roll eyes .... as is, have you disabled the laptop wireless if it is connected by cable (you can get all sorts of weird and wonderful loop effects!!!!)
Phil
Plusnet Fibre (Sep 2014), Essentials (Feb 2013); ADSL (Apr 2009); Customer since Jan 2004 (on 28kb dial-up)
Using a TP-Link TD-W9980 modem-router.
pj2014
Grafter
Posts: 103
Registered: 22-11-2013

Re: Laptop - Desktop - IP addressing issue

Hey all,
@nanotm -  yes the pc is wired via homeplugs and the laptop connects via wifi
The router is a Netgear DGN 3500 (its quite old now + solid) it has been flashed with some custom firmware (AMOD?) only to increase BB speeds but does not affect routing and/or other attached devices.
@journeys - unfortunately, as the router is flashed it is not up to date but I'm sure it 'exceeds' the last known firmware pushed out by Netgear.  (I think the firmware was built on/around the last known official firmware)
I tried with static IP addressing too. I gave them fixed IP's outside the dynamic range so no other interference or 'competition' for its IP. The yellow triangle/loss of IP address still occurred.
@PeeGee - Yes actual loss of IP address. When I check IP config it comes up with 192.168.0.6 (preferred in IPV4) I think. I check by logging into the router (from the laptop or elsewhere) and the PC is not seen (yet when I power down the laptop the network symbol (on the PC) becomes normal/network properties shows a link from PC - Internet and all is well again). They get different ip addresses and I have tried assigning static IP's as well just in-case it was an issue. But sadly that did not help either.
Connection setup
- router downstairs connected to various devices wired/wireless both directly and indirectly through switches (all work fine).
- A home plug near the router and a home plug upstairs. This home built pc (and previous HP desktop) connected directly to the home plug upstairs and works fine.
- The Toshiba laptop when powered on obtains an IP address and then the yellow triangle appears on the home built pc, power laptop down and PC re-gains an IP.
- In the meantime, another acer laptop I have 30 cms away works fine and has/encounters no issues.
pj2014
Grafter
Posts: 103
Registered: 22-11-2013

Re: Laptop - Desktop - IP addressing issue

Sorry,
Yes I also tried turning off the wifi on the laptop and used the ethernet port instead. I recall I had the same IP addressing problems. I will try that again though....
I recall doing something like that when I was trying to change the MAC on the laptop.
cheers
nanotm
Pro
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Registered: 11-02-2013

Re: Laptop - Desktop - IP addressing issue

what OS are the different machines running ?
just because your paranoid doesn't mean they aren't out to get you
pj2014
Grafter
Posts: 103
Registered: 22-11-2013

Re: Laptop - Desktop - IP addressing issue

The home build PC and previous HP desktop both with windows 7 x64
The Toshiba laptop previously with windows 7 x32 bit  and now with windows XP  (same problem on both OS's)
dick:quote
PeeGee
Aspiring Pro
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Registered: 05-04-2009

Re: Laptop - Desktop - IP addressing issue

Quote from: pj2014
- router downstairs connected to various devices wired/wireless both directly and indirectly through switches (all work fine).
- A home plug near the router and a home plug upstairs. This home built pc (and previous HP desktop) connected directly to the home plug upstairs and works fine.
- The Toshiba laptop when powered on obtains an IP address and then the yellow triangle appears on the home built pc, power laptop down and PC re-gains an IP.
- In the meantime, another acer laptop I have 30 cms away works fine and has/encounters no issues.

Any way to connect the new PC or the old HP without the homeplugs, alternatively, run the ASUS laptop via the homeplugs (wifi off) to see if the effect persists?
Does the effect occur with the Tosh running on battery (to eliminate the Toshiba PSU brick generating excessive noise)?
Plusnet Fibre (Sep 2014), Essentials (Feb 2013); ADSL (Apr 2009); Customer since Jan 2004 (on 28kb dial-up)
Using a TP-Link TD-W9980 modem-router.
pj2014
Grafter
Posts: 103
Registered: 22-11-2013

Re: Laptop - Desktop - IP addressing issue

Hey PeeGee,
Its difficult to move the home build as its a full tower full of bits and pieces and is super heavy! But....  I did disconnect it from the homeplug and connect up the Acer laptop (wifi off) (via homeplug) instead...  it connected ok received an IP address and seemed fine.
I then powered up the problem laptop (Toshiba via wifi) and lo and behold it also obtained an IP address. Both seemed to work ok, Acer laptop via homeplug and Toshiba laptop wirelessly.
I logged into the router and could see both connected and did ipconfig /all on both and seemed ok too.
I've attached a screen shot of the router login page as well as the ipconfig /all for the toshiba laptop....
I carried out the procedure above with both laptops powered by batteries (no psu blocks)
cheers
pj2014
Grafter
Posts: 103
Registered: 22-11-2013

Re: Laptop - Desktop - IP addressing issue

Ooops  attachments...