One laptop on network can't connect to internet

HI, I have three laptops connected directly to an Infinitum ADSL modem, Model HG530, using DHCP. One laptop is connected wirelessly. The other two use Ethernet cables. I also have an external hard drive connected to the modem.

One laptop is just there to run my magic jack. Up to a week ago, that was my good laptop. I had no problems with it ever.

Twice in the last week I've noticed an IP conflict, always on that laptop. I reboot and sometimes it goes away, sometimes not. Today it won't connect to the internet. I've rebooted the laptop, rebooted the modem, and replaced the Ethernet cable. It comes up for a while, then goes out again. I moved the Magicjack over to my good laptop and it's working.

An ipconfig on the laptop that can't connect, which we can call the Acer, shows:
IP address: 192.168.1.102
Subnet Mask: 255.255.255.0
Default gateway: 192.168.1.254

The modem shows a connection light on that laptop's input.

Thanks! I can also get access to the control panel of the modem if you need information from there.
Melody ScottAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

relliott66Commented:
Why not just, if possible, assign specific IPs to each laptop so that this problem won't occur again?  You can either do that on the laptop or assign one at the modem/router.  Do you do any multibooting in that laptop?  Meaning multiple OSs...  As to the address, it definitely is a valid IP and not one that gets assigned when a system cannot connect.
kuzmanovicbCommented:
Check other computer to see does it have the same numbers as your acer except last few digit from ip address.

If it does than You can you try to set your ip on acer manually to:
IP address: 192.168.1.210
Subnet Mask: 255.255.255.0
Default gateway: 192.168.1.254

If it doesnt try to set it like the other one but change ip address last digit.

help on how to set ip on windows xp: http://www.home-network-help.com/set-ip.html
Melody ScottAuthor Commented:
thanks - why would the acer get an IP address from the modem that conflicts with others on the system? Seems odd to me..
Your Guide to Achieving IT Business Success

The IT Service Excellence Tool Kit has best practices to keep your clients happy and business booming. Inside, you’ll find everything you need to increase client satisfaction and retention, become more competitive, and increase your overall success.

kuzmanovicbCommented:
can you tell me what mac addresses do you have on laptops?
how to find your mac address: http://www.wikihow.com/Find-the-MAC-Address-of-Your-Computer
adibob2005Commented:
are all the compters on your network getting ip automatically or u have asigned them manually ?

Melody ScottAuthor Commented:
All automatically. Sometimes I turn two of them off and leave the Acer on.  Then turn the other two on in the morning.

I assumed that the device assigning IP addresses would be aware of IPs already assigned, is that  incorrect?
lost_enigmaVP of IT infrastructureCommented:
looks like problem of DHCP server.
What is the scope assigned for DHCP? It is enough addreses?
DHCP is responsible to handle requests from PCs (it is broadcast requests). Except scope problem with addresses - 3 possible reasons come into my mind
1) If this DHCP requests is blocking by some reasons on your router,
2) DHCP do not reply on requests in time
3) somebody connected with static IP (also think about Wi-Fi, it can be hacked if you are not using WPA2 encrypt.)

as solution for the 1 and 2 - can you make static address lease for this laptop on DHCP SERVER (!)?

about 3:
Check that nobody connected to your wireless except you :)
Hot to check -
You can check DHCP leases (there should be only 3, if you use only 3 laptops) and check Wifi cliens, if you wifi allow this.
Sampat1983Commented:
check out the dns settings on laptop. if its not assigned properly, manually enter 192.168.1.254
lost_enigmaVP of IT infrastructureCommented:
Sampat1983
how DNS can make influence on IP address conflicts?
...
Sampat1983Commented:
its been told that there it can access the router web page. that means the until router is clear. then the only problem will be dns.
Melody ScottAuthor Commented:
Ok, My modem/laptop says:
first address for DHCP: 192.168.1.101
Number of addresses: 153

Primary DNS server 0.0.0.0
SecondRy DNS server: 0.0.0.0
Remote DHCP server: N/A
DHCP lease time: 3 days 0 hours

Then it assigns for the two laptops currently powered on:

My primary laptop: 192.168.1.101
Acer: 192.168.1.102

But the acer is showing an IP conflict. And it says when I run ipconfg, 192.168.1.102.

The modem/router doesn't show more than one machine getting DHCP. I'lll attach a screenshot, it's in Spanish but I can translate anything I haven't already. screenshot of DHCP screen on modem/router
Melody ScottAuthor Commented:
Ok, my husband is up. He connects wirelessly.  His laptop is not showing up on the DHCP screen of the router.

His IP is 192.168.0.100, default gateway 192.168.0.1.

Is that normal?
relliott66Commented:
No, not normal.  Is he connecting to someone elses?  I would set those IPs to estatico on your router, this way they will ALWAYS be assigned to those machines.  Once you have set to estatico go ahead and reboot each and see if you still run into the same problem.  As to his, check and see who's router he is connected to :)  Could be that there is someone in your neighborhood who doesn't have security on.

Buena suerta

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
relliott66Commented:
suerte ;)
Melody ScottAuthor Commented:
Gracias. ;)

OK, I had forgotten that I also had my D-link wireless router plugged in, and my husband was connecting to that. Now it's unplugged, he's connected wirelessly to the modem, and I have rebooted the Acer and his laptop.

Now I'm showing no system error, and the Acer can connect to the internet. Hurray!
Melody ScottAuthor Commented:
OK, I need you experts to tell me who gets the points here!
relliott66Commented:
Glad you got it fixed.  It's your determination on who added most value to resolve your issue.  You can also assign "assist points" as well as the main one.
lost_enigmaVP of IT infrastructureCommented:
may be the same address configured manually on wireless interface?
Melody ScottAuthor Commented:
Might be, I have unplugged the D-link,, which also gave out addresses via DHCP, I think that's where the problem was, and maybe it had a static IP.
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Switches / Hubs

From novice to tech pro — start learning today.