HELP! Can't Connect to Internet

[boomerang4625]

I have problems connecting to the Internet depending on how I hook up my computer system.

HOOK-UP #1 :
Cable Line-In to Modem In
Line-Out of Modem to Computer “A” Ethernet Input
THIS WORKS

HOOK-UP #2 (Did work at one time)
Cable Line-In to Modem In
Line-Out of Modem to Router In
Line-Out of Router to Computer “A” Ethernet Input DOES NOT WORK
Line-Out of Router to Computer “B” Ethernet Input DOES WORK
Computer “C” which uses a wireless card DOES WORK
*************************************************

I attempted to install my ISP high speed software on Computer “A”.
In trying I got the following message.

Network adapter's TCP/IP setting may contain outdated IP information.
Renew IP configuration.
Next was an automatic attempt to reset TCP/IP settings which failed.

I attempted to install my ISP high speed software on Computer “B”
And it worked with no problem.
****************************************************

Question: What is the problem with Computer “A” that prevents me from connecting to the Internet when using HOOK-UP #2. Is it as simple as making a change to the Windows XP Internet Connection for Computer “A” to fix the problem? Or is this a Hardware issue? Computer “A” by the way is a HP Pavilion a305w.

 

[jpretorius]

Could be the Cat5e cable you used in Hook UP 2 to connect to computer A or even one of the ports on the router. To test use HOOK - UP # 2 again but swap the Cat5 cables between the router and the computers A & B and also try different ports.

Do you have NAT configured on the router? if you are not sure what this means, go to command prompt and type in ipconfig. Let me know what your ip address is on the machines that work -- It could be that your ISP is only issuing a maximum of 2 ip's therefore when all three machines are hooked up only two are receiving an ip. If you have NAT configured this won't be the case. If computer A works when connected in HOOK UP 1 is no problem with the hardware on computer A.

 

[boomerang4625]

Thanks for your help jpretorius.
Well, All the cables and ports are working just fine. That was the first thing I checked.
I did check the IP addresses on the 2 computers that work,
and their IP addresses ARE DIFFERENT.

In discussing this ordeal with a friend of mine, he seems to think that I may need
to reset the IP address to work with the router for Computer “A” being that this
IP address was originally setup to work with the
connection coming directly out of the modem. (as indicated in Hook-Up #1)

What Is Your Take On This???

 

[boomerang4625]

I just finished checking the IP Address on all 3 computers
and I get (3 different IP Addreses).

 

[boomerang4625]

In reviewing a previous post of athlon64fx it was mentioned
to insert Windows XP cd and choose the repair installation to
bring back my TCP/IP network files.
Question: By doing this will it affect other files on my computer?