Home Network has Died, But Can Connect 1 PC...Stumped

[cohenfive]

setup:
home wired network with 5 pc's, comcast cable modem via linksys befsr81.

never had a problem until a few weeks ago when our network went out. everything seemed good and i had comcast test the modem which they said was receiving and sending data. i tried connecting the modem directly to one of the pc's and low and behold i had a connection. the minute i connected the modem to the router and then to the pc no service anywhere on the network. i replaced the patch cable between the modem and the router and for some reason the network came back. i thought i was so smart replacing the cable....

well today i have the same problem--no connection anywhere in the house. thinking it must be a defective router i bought a brand new befsr81 and set everything up...same result. with the modem connected to the router there is no service anywhere in the house, but if i connect the modem (with the same patch cable) directly to our pc the connection (like now) is perfect. i tried disengaging zone alarm and norton but that didn't help.

i think i've eliminated hardware as an issue but have no idea what sort of software conflict on my pc could possibly disable the network. when i go to control panel-internet connections, it says the local area connection is connected (even though i have no service), but if i try to repair it, windows can't get a new ip address and i'm still dead.

sorry for the long winded description but i'm really at a loss on how to fix it and don't even know where to turn. any suggestions would be appreciated.

 

[Ctrackstar126]

I would try uninstalling the zone alarm and then reapplying it just to make sure. I know theres a lot of problems with that firewall and your problem was the same problem I had about a week ago.

Also are you set up on DHCP or static

also ipconfig and see if theres an ip address etc and that you have your default gateway set to your router

 

[cohenfive]

just ran ipconfig:

as for zonealarm i did disable it...you think i should completely blow it away? any way of checking to see if it's not allowing connections without resorting to that?

says addy is assigned by dhcp.

how do i see if the def gateway is that ip address?

thanks!

 

[cohenfive]

ok, as another test i just tried connecting my wife's lappy to the cable modem...directly via patch cable from the modem just as my pc will work.

i had the same problem as with the overall network--says it's connected but there is no connection. when i tried to repair it, windows was unable to assign an ip addy so no go...

now i plugged the same cable into my pc and voila i'm back on the net!!!

but now i'm probably more confused than ever. my wife's lappy does not have a firewall by the way...

 

[JackMDS]

Is it Comcast Cable Internet?

If it is, try to clone the MAC number of the PC that works directly with the Modem to the Router, How to Fix Cable/DSL Internet authentication (password).

:sun:

 

[cohenfive]

Originally posted by: JackMDS
Is it Comcast Cable Internet?

If it is, try to clone the MAC number of the PC that works directly with the Modem to the Router, How to Fix Cable/DSL Internet authentication (password).

:sun:

yes it's comcast cable internet. i will see if i can figure how to do the above. very strange set of occurrences however...do you also recommend a complete uninstall of zone alarm? i've tried disabling it to no avail...

 

[JackMDS]

I personally do not like Zone Alarm. Every release comes out with its own peculiarity of Network Disturbances.

For money I rather have the Firewall part of NIS.

For free? See here, Freeware Security suit for Internet Connection Protection.

:sun:

 

[Ctrackstar126]

Ive heard about a lot of problems with zone alarm and Ive seen some issues first hand.

The reasons I said get rid of it completly is because I saw the same problem where the network was trying to aquire an Ip but wouldn't

Just uninstall it and if it doesnt fix it reinstall it.

 

[boomerang]

Find the reset button on your router and try that. If it doesn't work, your router is hosed.

 

[tweekah]

From what i've been reading.
You're from the east bay (Hayward/SL/Castro Valley). Your probably have a Motorola SB5100 modem (those things have a habit of marrying MAC addresses). Jack's suggestion is correct. In laymens terms, MAC addys are "unique" identifiers on network interface cards sort of like a serial number. Zone alarm may be causing a problem, disable it!

First connect the modem to router using the internet/WAN port on the router. Then unplug the POWER to your modem (this is important), but leave the router plugged in. Then plug any computer into one of the remaining LAN ports. Do an ipconfig on the computer and make sure you pull a valid private ip such as 192.168.1.100. Browse to your router's config page using an internet browser going to http://192.168.1.1 Default login is blank/admin or admin/admin once you are inside your router's config page. Goto the status area. You should see something like DHCP with a current ip of 0.0.0.0 with a release and renew button at the bottom. Now go ahead and plug the POWER to the modem back in. Give it a min to pick up sync and do its thing.

Click the DHCP renew button on the bottom, and you should see 67.180.X.Y as your ip address. Once you see your public ip on your router's status page you are in good shape. If you are getting a 0.0.0.0 ips you will need to clone the MAC address of the computer that works into your router. The purpose of leaving the modem off is so it will release that MAC address it remembers.

Once you have the 67.180.X.Y ip on your status page you'll need to probably renew your dns to surf the "INTARWEB" correctly on your pc. You can either reboot the PC or release and renew in the command prompt. You then can add the other 4 computers one by one. Make sure they release/renew - windows repair is the same thing I think. Let us know how it goes.

 

[cohenfive]

thanks everyone...i'm going to uninstall zonealarm and then try tweekah's suggestions...

it's not the router as i bought a new one today and had the same issue...it's got to be some sort of weird software issue...i'll keep my fingers crossed...

oh, and yes i'm in the east bay (lafayette/martinez area) and have a sb4220 modem...

 

[cohenfive]

ok, here's what i've done so far..no luck..

unplugged modem-router plugged in

internet:

auto config: dhcp
ip 0.0.0.0
def gateway 0.0.0.0
dns 0.0.0.0

plugged in modem and hit dhcp renew

no changes to internet status above!!

oh, also checked under system:

mac cloning is disabled

one other item, not sure if it's related:

when i shut down the pc, i get a message that it needs to end the following program:

t1faxevent

i've never heard of this app and it doesn't show anywhere...

 

[cohenfive]

one more thing.....

is there anyone here that's an expert in this stuff that lives in the bay area--i'm willing to pay someone to come out and help if i can't figure this out tomorrow. my wife's business is run out of our house and she needs internet access in her office. also my kids need acess.

thanks again!!

 

[tweekah]

I bet I can throw a rock and hit your window and am fairly confident I can walk you thru it over the phone. PM me you number and i'll get you up and running no charge.

 

[boomerang]

In the MI area, Comcast is only concerned with the MAC address of the modem. That's what it uses for authentication.

Evidently, in the OP's area, they issue or issued a modem that must be setup to clone the MAC address of the computer originally connected to it.

So is this modem specific? In other words, with a different (say, newer) modem this would not be an issue in his area?

What a customer service headache for Comcast.

 

[cohenfive]

tweekah, pm sent...

headache for comcast, how about headache for me! they have been zero help so far...

 

[bruceb]

Quite often with Cable Modems you must power them down for a few hours or overnight
if the IP address gets messed up or if you change Routers ... Most cable companies use
ip's with a lease of 24 hrs or so .... Comcast can tell you if the IP into the router is
Static or Dynamic (DHCP) ... they can also Release & Renew your IP Lease for you
after you have changed or reset your Modem or Router

 

[cohenfive]

just wanted to thank all of you for the advice. i got on the phone with tweekah this afternoon and we were able to figure it out. it ended up being a simple problem but how it came about is anyone's guess.

it turns out there was a conflict between the wireless router/access point i was using on the network and the wired router. i've been using this setup without a problem for at least a year, but sometime a few weeks ago between power failures, comcast outages and possibly comcast system changes the settings for the wireless changed and started conflicting with the primary wired router. once we figured that out all we had to do was disconnect the wireless and reboot everything.

this is a great site and it's great to be able to share knowledge this way. muchas gracias tweekah and everyone else!

 

[John]

Sorry for the bump, but how come you didn't mention having a 2nd router connected in any of your posts? Someone would have recommended disconnecting it a long time ago.

 

[cohenfive]

Originally posted by: John
Sorry for the bump, but how come you didn't mention having a 2nd router connected in any of your posts? Someone would have recommended disconnecting it a long time ago.

john, you are right and i deserve the 'bump'....the reason i didn't mention it is i forgot about it. also it had worked perfectly until a couple of weeks ago so it didn't cross my mind until we got into it.

but thanks!!