Internet connection dropping out

[Mike89]

Got this weird problem I'm trying to solve.

Two computers (XP Pro SP3) running off a Vonage Router (Linksys RTP300) from a Comcast Surfboard modem.

One of the computers is experiencing the internet dropping out intermittently. Sometimes when booting up, there is no connection. The double monitor icon in system tray has the red X through it. Sometimes it's trying to connect where the red X is appearing and disappearing every few seconds or so. Then sometimes it will just work fine. While all this is happening, the second computer is not experiencing any of connection issues at all.

At first I thought the motherboard nic was failing or something. I bought a pci nic card and hooked it up. The same problem still exists with it. I also have replaced the cable to this second computer with no change.

Can the router be causing this? As I said, the second computer that is also hooked to this router is not experiencing any internet connection problems. When the connection was not working on 2nd computer, I even tried disconnecting the cable from router to 1st computer and plugging 2nd computer cable into same jack without 1st computer being hooked to it. No change. It seems to work when it wants to and doesn't when it doesn't.

Could something in XP on this 2nd computer be causing this problem?

Dunno what the hell is going on here, and dunno how to even know what's causing it so I can fix it.

[Sava700]

bypass the router to the troubled computer to rule the router out. If its still doing it directly to the modem then its the computer and you will need to diagnose just that vs rackin your brain about the router.

Also post your signal levels from your modem

http://192.168.100.1/signal.htm

[Mike89]

Tried running 2nd computer straight to modem. Computer would not connect, this time getting a yellow exclaimation on the task bar icon. Hooked it back up to the router and then got a connection. This thing has a mind of it's own. Seems now to point to Windows XP but I don't know what to do to trouble shoot that.

Modem check:

Frequency 729000000 Hz Locked
Signal to Noise 33dB
QAM 256
Network Access Control Object ON
Power Level 5 dBmV
Channel ID 3
Frequency 25350000 Hz Ranged
Ranging Service ID 2018
Symbol Rate 3.200 Msym/s
Power Level 43 dBmV


Another thing I notice. When it is having problems connecting, it is after a cold startup. After the computer stays on for about an hour, it finally connects. Once it gets connected, it stays connected (until next turning off/on of the computer).