Network experts come in - help with Linksys router!


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StreetShooter

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#1
I have a Linksys BEFSR41W connecting two PC's (Cat5 cable) which are sharing a Starhub Maxonline connection.

One PC is a P4 running Win98SE. The other is a newly-built Celeron (Gigabyte 81845GE-RZ with onboard NIC (Realtek)) running Ubuntu.

The Win98SE PC has no problem connecting to the router and internet, whether or not the Ubuntu PC is switched on or connected. When the Win98SE PC is switched off, the LED's on the Linksys router go off.

The Ubuntu PC cannot connect to the router or internet when the Win98SE PC is off. The activity/link LED for the Ubuntu PC connection on the Linksys router will blink furiously (even when the PC is off, but the mains power supply is on). The LED's will only go off if I switch off the mains or disconnect the Cat5 cable from the Ubuntu PC.

When the Win98SE PC is switched on and connected, both LED's will be on and the furious blinking will stop. The Ubuntu PC will then be able to connect to the router and the internet.

When the Ubuntu PC is connected directly to the Starhub cable modem, I am able to surf the internet.

I've narrowed it down to a hardware problem between the onboard Realtek NIC on the Gigabyte motherboard and the Linksys router. Somehow the Linksys router requires a second PC to be connected and switched on before it will work with the Realtek NIC. I can still surf the internet with the Ubuntu PC, but the Win98SE PC has to be on at the same time, or I have to connect the Ubuntu PC directly to the Starhub cable modem, bypassing the router. Not really a problem, but defeats the purpose of having a router.

I don't think it's a DHCP problem because I have tried setting the Ubuntu PC to both DHCP and a static IP, and the same problem occurs.

Any ideas for a workaround would be appreciated.

I have tried installing a second PCI bus NIC on the Ubuntu PC but somehow the PC will refuse to even boot up when the Cat5 cable is connected to this NIC. Disconnecting the Cat5 cable from the NIC will allow the PC to boot up. Could it be a grounding problem???

Thanks for any input.
 

Del_CtrlnoAlt

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#2
i think your ubuntu is set to entering the net via another computer. so your win98 have to be on then it will allow connection. check your ubuntu connection.

btw i've never used a ubuntu b4, wats tat? ;p
 

eawtan

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#3
Some thoughts:

With the router & ubuntu - check the ip address of the ubuntu machine, ensure that dhcp address and dns is correct (ifconfig and /etc/resolv.conf)

With router & ubuntu on fixed IP - is the dns setup correctly? (check /etc/resolv.conf)

With router & ubuntu only (on both fixed IP and DHCP) - check if you are able to "ping" the router, check if you are able to ping an outside address "eg clubsnap.com" using only the ip address.

When using a PCI NIC, try disabling the onboard NIC in the BIOS.
 

StreetShooter

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eawtan said:
Some thoughts:

With the router & ubuntu - check the ip address of the ubuntu machine, ensure that dhcp address and dns is correct (ifconfig and /etc/resolv.conf)
Ubuntu set to DHCP - IP address assigned by router (but only if Win98SE PC is switched on). For static IP I used one which is not within the DHCP server range.

With router & ubuntu on fixed IP - is the dns setup correctly? (check /etc/resolv.conf)
Static IP works if Win98SE PC is switched on at the same time, so I assume no problem. Will check later, thanks.

With router & ubuntu only (on both fixed IP and DHCP) - check if you are able to "ping" the router, check if you are able to ping an outside address "eg clubsnap.com" using only the ip address.
Can ping the Ubuntu IP, cannot ping the router IP. When trying to logon to the router IP, "Connection refused" error.

When using a PCI NIC, try disabling the onboard NIC in the BIOS.
Yes, I did that.

Thanks for the thoughts. Will poke around some more at lunchtime.
 

Wai

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#5
this is interesting...

the last time when i saw the router LED blinks furiously was due to the cable fault.

but once u turn on the Win98 machine, it works fine leh

may be u can try another port or upgrade linksys firmware
 

ellery

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#6
swop the port around.this is oxymornoic but check the manual to see if there is any port 1 that must be active - as I said it makes no sense.
 

espn

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#7
Well, not meaning to be funny, try resetting the router to it's default settings and try.
 

eawtan

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#8
Another suggestion...

Get 2 copies of Knoppix Live CD, and boot both PCs using these CDs. Again trying both connected and individually.
 

espn

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#9
eawtan said:
Another suggestion...

Get 2 copies of Knoppix Live CD, and boot both PCs using these CDs. Again trying both connected and individually.
That's one way.
 

Jan 23, 2005
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#10
Can ping the Ubuntu IP, cannot ping the router IP. When trying to logon to the router IP, "Connection refused" error.
Not sure if there's a link (pun not intended)... I've had the problem that both the router and the cable modem may act as DHCP servers, causing interesting problems that would also depend on the timing/order in which one switched on the different devices. Sometimes talking to the IP that was supposed to be the router really meant talking to the cable modem. No more of these problems since I disabled the DHCP server on the cable modem.
 

espn

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LittleWolf said:
Not sure if there's a link (pun not intended)... I've had the problem that both the router and the cable modem may act as DHCP servers, causing interesting problems that would also depend on the timing/order in which one switched on the different devices. Sometimes talking to the IP that was supposed to be the router really meant talking to the cable modem. No more of these problems since I disabled the DHCP server on the cable modem.
Cable modem doesn't assign DHCP, however, itself is a NIC client, ie: it grabs the IP from the router (SCV's) and behaves like a gateway in this setup.

The DHCP portion here is only limited to the router sending out the IPs to the end-user devices connected.
 

espn

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LittleWolf said:
I can assure you: my Motorola cable modem does it by default, in full accordance with the manual.
That's unless of course your modem has a built in router functionality, then yes, it's possible.
 

Del_CtrlnoAlt

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LittleWolf said:
I can assure you: my Motorola cable modem does it by default, in full accordance with the manual.
yours is which 1? iirc, i think my 4200 (think should be that model... the 30mbps model...) have a built in DHCP, and i went into the configuration to disable it.
 

StreetShooter

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#15
OK more details.

I find that when I physically disconnect the Ubuntu PC, the Win98SE PC cannot connect to router or internet. If the Ubuntu PC is connected but not switched on, the Win98SE PC can connect. The difference between the two is that the Ubuntu PC's LED remains on even though it is switched off (as long as the cable connection is there), but the Win98SE PC's LED goes off when it is switched off.

To summarize, BOTH LED's on the Linksys router must be on, then there is no frantic blinking and connecting is possible. When only one LED is on (either Win98SE PC only with Ubuntu PC disconnected, or Win98SE off) then no connection and no surfing.

This did not happen previously (the Ubuntu PC replaces a Dell WinXP system, which also kept the LED's on). Will try to connect back the Dell WinXP system and see if the problem persists. If so, then I can only conclude that I may have fried the Linksys (through the Cat5 cable - is that possible?) while setting up the new Ubuntu PC. I had some strange power problems initially.

Thanks for all the ideas. I tried switching the ports around (almost every possible combination). I also tried disabling the router's DHCP server. The Starhub cable modem has no DHCP server, so cannot disable, or else I donno how).
 

Wai

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#16
StreetShooter said:
Thanks for all the ideas. I tried switching the ports around (almost every possible combination). I also tried disabling the router's DHCP server. The Starhub cable modem has no DHCP server, so cannot disable, or else I donno how).
last resort, try another router, if u want i have another linksys to spare for u to test out
 

Ola

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#17
espn said:
Well, not meaning to be funny, try resetting the router to it's default settings and try.
Have you try what espn suggested?
You should start from scratch now.
Reset the router to it's default setting and connect only 1 system to the router and the cable modem. (Removed the cable too)
Configure and test the setup and make sure this configuration work first.
Remove the working system (including the LAN cable) and connect the second system to the router on a different port.
Configure and test the setup and make sure this second configuration work.
Connect back the first system to the router.
Test to see if it work fine.

The difference between the two is that the Ubuntu PC's LED remains on even though it is switched off (as long as the cable connection is there), but the Win98SE PC's LED goes off when it is switched off.
This is normal especially for system with on board LAN.
 

espn

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#19
+evenstar said:
I'm not sure what's with my router also, but the moment my modem is connected to the router, the internet LED will start blinking non stop. Same goes to when any computer is connected to the router
Erm...that's common... data transfer is going on that's why the light is blinking non-stop... :sweat:
 

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