blinking ethernet light

psyper · 28-11-2003, 15:56

I have an ntl:home boardband 100 modem and its connected to a D-Link Ethernet Broadband router which in turn connected to my 3 PC's.

They have all been able to connect to the internet and each other for the last year and a half without a problem. That was until I had to power them down to redo the cabling round the back of my computer (they only got disconnected for 5 seconds or so).

Anyway - now all the lights: WAN (cable modem upload) and the 3 PC connections are flashing together at the same time about twice a second - this is also the same on the Ethernet light on the cable modem!
When this happens none of the computers except one can connect to the net - and it cannot see the other 2 computers on the lan - whereas the other 2 computers can see each other but not the internet and not the computer which is connecting to the internet!! :S
I've rebooted all my machines and it seems like the first one to boot up gets the internet.

When I connect a single machine directly to the cable modem (bypassing the router) I get a connection to the net but this is slower than normal and the ethernet light blinks like mad even when the upload and download lights arent lit.

Anyone have any suggestions?

Stuartbe · 28-11-2003, 16:03

First I would check that a xover cable has not been put between the router and modem as this can cause problemss. I would also reset the router as these kind of devices can crash for no reason. You can usualy restore factory settings via a reset button on the back of the router.

I would also check that the cable modem is plugged in the wan connection and the pc's in the lan connection. If they are reversed it could cause this problem.

HTH

Stuart

Stu038 · 28-11-2003, 16:07

Sounds like the router config to me mate. I would suggest having a look there first.
Also check the TCP IP properties of the ethernet cards on you PCs to make sure that theyre still right.

**Chris** · 28-11-2003, 16:22

I'm not an expert, but you said they were only disconnected from the power for about 5 seconds? - This may be the problem. Try powering down the whole lot for more than 30 seconds and then starting again. I have found that any problem with my modem or the TV's set top box that requires a re-boot, requires the whole lot to be properly switched off for a while for the re-boot to be effective.

psyper · 28-11-2003, 16:35

Thankyou all for your quick reply - never expected to get an answer so quickly!!

Firstly all the network cables are the same that I used before the problem - they are all standard cat5 with no x-overs.
I've checked the TCP-IP settings and they are all the same.
I cant see the router being the issue cos when I bypass it I'm still getting the problems but I have done a full reboot of the router and modem (30 seconds) then powered up the computers.

Just an extra note - when the cable modem isnt connected to the router the computers all see each other on the network and are able to send and receive files to each other - the router acts all normal with the lights blinking only when I'm sending packets to other computers on it. Its when I hook up the modem does it go haywire - all computers but one looses their connection to the DHCP :S

28-11-2003, 16:35

Quote:

Originally Posted by towny

I'm not an expert, but you said they were only disconnected from the power for about 5 seconds? - This may be the problem. Try powering down the whole lot for more than 30 seconds and then starting again. I have found that any problem with my modem or the TV's set top box that requires a re-boot, requires the whole lot to be properly switched off for a while for the re-boot to be effective.

similar disclaimer about non expert status from me too, but afaik the same principle applies to switching back on - should be modem first & allow it to settle down, then the router & again let it settle down, then the pc's, i.e don't switch everything back on all at once.

Pierre Bordeaux · 28-11-2003, 18:14

It could be a corrupt configuration of the router --reset it to factory defaults (it may got corrupted when you switched it on and off)

If this does not solve the problem, remove all network cards from "system settings" and let the OS refind them and reinstall them one by one.

Good Luck!

Dooby · 29-11-2003, 09:31

if all the comps work when the router ISNT connected to the cable modem, are you sure you plugged the cale modem back into the WAN port on the router, I know it sounds like a dumb question and not wanting to imply anything about you, but its an easy mistake to put the cables in the back of the socket wrong...
theat might explain the connection issues, as the router and the cable modem may be arguing about who is the dhcp server...or something like that...

as to the slow browsing when you are connected directly, that may be unrelated...

Pierre Bordeaux · 29-11-2003, 09:44

Quote:

Originally Posted by Dooby

if all the comps work when the router ISNT connected to the cable modem, are you sure you plugged the cale modem back into the WAN port on the router, I know it sounds like a dumb question and not wanting to imply anything about you, but its an easy mistake to put the cables in the back of the socket wrong...
theat might explain the connection issues, as the router and the cable modem may be arguing about who is the dhcp server...or something like that...

as to the slow browsing when you are connected directly, that may be unrelated...

...but he said that the computer that boots first connects to the internet while the rest fail....

Dooby · 29-11-2003, 10:01

Quote:

Originally Posted by Pierre Bordeaux

...but he said that the computer that boots first connects to the internet while the rest fail....

well, the first comp to boot maybe getting its ip directly from the cable modem due to them all being connected to the same switch ( IF the cable modem is not plugged into the wan port )

it may be worth checking what the ip of the computer that connects first is, and checking whether the DHCP server on the router has got disabled somehow

The_real_dj · 29-11-2003, 11:06

Just what i was thinking dooby.

What ip address is the working internet machine getting?

If its 192.168.x.x or 10.x.x.x then its getting the ip address from the router if its anything else then it looks like the DHCP server in the router is disabled!

psyper · 29-11-2003, 16:21

Okay - I'm pretty sure I wouldn't connect up the wrong cable to the wrong port and I haven't disconnected any cables before this problem started occuring but I had been unplugging and swapping them around while I was diagnosing what was going on - so just to be on the safe side I pulled out all the cables and the modem one was connected up to the WAN on the router. - so that ruled that out. I was kinda hoping that I was an idiot and did that cos then atleast it would solve the issue.

When I connect up a single computer to the modem the Enet light does blink in the same way as it does when its connected to the router. And so does the light on the network card in the back of the PC - I've rebooted the computer and did an ipconfig and it the default gateway with an ip address. If I boot up any other computers then they dont get assigned one - even when I release the ip address or reboot them again. Its only when I shut down the PC with the gateway assigned and boot up another do they get the gateway and the connection.

Stu038 · 29-11-2003, 21:20

I had a very similar problem some time ago after a power cut, only the first PC to finish booting would connect to the net but all worked individually when connected straight to the modem. The problem turned out to be that the router had reset its own IP address to the same as the cable modems internal one. Took a couple of days to work out cos it didnt even occur to me to actually look at that one on the tables

as I thought that duplicate IPs on the same network would stop all trafffic. Once I'd reset it a quick reboot of the PCs and everything was sorted

psyper · 30-11-2003, 09:50

Thanks for that. Does sound like my problem to a T. It might explain why I'm getting conflicts with just the one computer connected to the modem - if its been assigned a dodgy ip by the router then it might be arguing with the modem too.

Now all I have to do is find the router manual and work out its ip address to configure it via IE ....

psyper · 18-12-2003, 09:21

Just an update on this. I found the manual for the router and tried to connect to it to see if its configuration is up the creek - I was unable to ping it at all even when I just connected one machine to the router with no WAN. I also tried the factory reset switch but that didn't seem to do anything (and yes I followed the instructions by the letter - holding it down for 12-15 secs etc). In the end I decided to go out and get a wireless router - I have a wireless card in my laptop for when I'm round my gf's house and I was planning to get a wireless router for my house too. I was able to get all my machines connecting to the internet at the same time with this - [so does anyone wanna buy a knackered router!?! lol].
The bad connection issues I was getting earlier on this post are still here but I've found out that all my friends are getting the same issue here (Luton, Stevenage, Hitchin) and by some of the topics here it looks like an NTL issue rather than my hardware - oh hum!

Special thanks goes to all those that have helped me with this issue - the replys were both very prompt and very very helpful, thanx