Member Avatar for Collypso

Hello, I'm having this weird problem with my network configuration. I had my modem going into a wireless router and a network cable going from there to a switch and finally into my computer and the neighboring room's computer. I disconnected the router to move it somewhere else and now it won't work even though the cables and the devices remained the same.

So I gave up on the router and connected my switch to the modem and now my win7 computer can access the internet, but the computer in the other room which has XP can't connect.

I changed routers, I changed cables, I reset computers, routers and modems. Nothing works, it's either my computer has connectivity and the other one doesn't or neither does. I'm driving myself insane staring at blinking lights, is there something wrong with my network?

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  • Latest Post Latest Post by Docktor D

Dani AI

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A likely root cause for the symptom described — Win7 works when the switch is tied to the modem but the XP box does not — is that consumer modems typically give out a single routable connection. A router’s job is to take that single connection and share it (NAT/DHCP) so multiple machines can access the Internet at once. Without the router in the chain the modem will usually hand a usable address to the first device it sees, and a second machine will be left without a DHCP lease or get a self‑assigned address. Some ISPs or modem firmware also bind the lease to a device MAC or require the router to perform the ISP login, which explains intermittent behavior when devices are swapped. This is consistent with ’s suggestion to power-cycle and check address info, but it’s the single‑address/ISP-binding behavior that usually causes the problem.

Practical options: restore a router between the modem and the switch so the router takes the public connection and the LAN (switch + PCs) are on its private network. If a router is not available, either request additional public IPs from the ISP (rarely free) or enable the modem’s built‑in routing/NAT/DHCP if that model supports it. Also check whether the ISP uses PPPoE or similar authentication — if the router was handling login, removing it will break multi‑client access.

XP-specific checks to narrow the fault: confirm the XP NIC is set for automatic address assignment, verify the NIC driver is current, temporarily disable personal firewalls/security software, watch the link/activity LEDs, and try a direct modem connection with the XP box to see whether it gets a public address. A self‑assigned address (the auto‑assigned range) indicates DHCP failure and points back to the modem/ISP single‑address issue.

In short: symptoms point to modem/ISP addressing rather than a Windows‑only fault. Restoring router NAT or changing the modem/ISP setup will resolve it; modem model and ISP auth method will narrow the definitive fix.

Member Avatar for Docktor D

Hello, I'm having this weird problem with my network configuration. I had my modem going into a wireless router and a network cable going from there to a switch and finally into my computer and the neighboring room's computer. I disconnected the router to move it somewhere else and now it won't work even though the cables and the devices remained the same.

So I gave up on the router and connected my switch to the modem and now my win7 computer can access the internet, but the computer in the other room which has XP can't connect.

I changed routers, I changed cables, I reset computers, routers and modems. Nothing works, it's either my computer has connectivity and the other one doesn't or neither does. I'm driving myself insane staring at blinking lights, is there something wrong with my network?

Post back the Brand of your router

take cable from modem into WAN on the router. plug cable from router into switch, plug computers into switch.
Do all this with power off to everything
Power up modem wait 1 minute
power up router wait 1 minute
power up switch - power up computers
if still no connection
Go to command prompt type in ipconfig /all
on both computers post back info
should have gateway of 192.168.x.x and
subnet mask of
computers should have 192.168.x.x
where the x's are could be from 1 to 3 numbers
regareds
Dock

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