connecting two routers - Comcast cable modem connected (cascade) into router which then connected to another router

I have a new Comcast cable modem connected to the Internet port of a generic router, I have two PCs cabled from the lan ports of this first router and from another lan port on the first router I am running a cable to a second router which will have two PCs cabled to it.
1) should I connect the cable to the lan port or internet port of second router ?
2) should I change the DHCP setup for either of the routers?
3) should I change the working mode, ie Router, Gateway, etc, on either router?
4) should any or all of the PCs be set to - obtain IP address dynamically, or should any or all have fixed IP addresses?  Three of the four PCs are Windows XP and one is Vista.
I have tried several ways of connecting the routers and changing various settings and I can get everything to work fine for a few minutes and then the two PCs connected to the second router always get disconnected, even if they are just sitting idle.  The PCs connected to the first router are always fine and ONE PC connected to the second router is always fine, the problem starts when I connect a second PC to the second router.  This seems like an IP address conflict, are the dynamic IP addresses handed out by the cable modem?  or the first router?  I am look for the correct way to do this instead of trying this and that and experimenting, I have run out of time and need to know the correct way to set this up.
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rcheneyAsked:
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newborn1281Commented:
The second router what is the name of it if its something like linksys you can use it like a switch bypassing routing options. Just turn off DHCP on it and make router 1 as DHCP server.
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Don JohnstonInstructorCommented:
>1) should I connect the cable to the lan port or internet port of second router ?
LAN port.

>2) should I change the DHCP setup for either of the routers?
Disable DHCP on the second router.

>3) should I change the working mode, ie Router, Gateway, etc, on either router?
No change on first router. No need to change anything on the second since you're not connecting to the WAN port.

>4) should any or all of the PCs be set to - obtain IP address dynamically, or should any or all have fixed IP addresses?
I would use dynamic. Let the PC get their IP addresses from the DHCP server (first router).

>his seems like an IP address conflict, are the dynamic IP addresses handed out by the cable modem?  or the first router?
Sounds like it to me. The IP addresses should be handed out by the first router. Make sure ALL the PC's are set to "obtain IP address dynamically". Make sure the second router has it's DHCP service disabled.
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newborn1281Commented:
just plug in cable from router one in any Ethernet port on router 2 LAN ports do not use WAN it should bridge two routers and router 2 will act as switch but turn off dhcp on second router.
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jasfoutCommented:
Hello,
I am assuming you want the PCs connected to Router2 to be on a separate(unreachable) network than the PCs connected to Router1.
If yes, setup DHCP for the LAN side of both routers.  Set the WAN connection on Router2 to connect via DHCP.  Yes it is that simple.
If not and you want PC connected to Router1 to be able to access PCs on Router2 then you must Turn off DHCP on Router2 and connect the routers using LAN ports only...leave the WAN connection disco'd
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cycle303Commented:
1. If you want to seperate the networks, connect the first router to the second routers WAN port
2. Make sure that you are using seperate networks for each router (192.168.1.X 192.168.2.X)
3. You could set them both to either and get it to work.  Try gateway on both to start.
4. I would use DHCP for all.  Again, make sure you are using 2 different networks.

Example.

ex.jpg
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jasfoutCommented:
Wow I was a little late...should have refreshed.

addition to above comment:
If yes, setup DHCP for the LAN side of both routers.  Set the WAN connection on Router2 to connect via DHCP.  Make sure the WAN connection of Router2 is connected to LAN of Router1. Yes it is that simple.
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rcheneyAuthor Commented:
Thanks for the advice, I really appreciate it, this problem is driving me crazy.
It does not matter to me whether the networks are separate(unreachable).  And it does not matter if PCs connected to Router1 are able to access PCs on Router2.  The only reason I have the second router is because I only have three cables going to three separate locations and one of the locations has two PCs and I cannot run more cables.  Three cables, three locations.
Location One has 1 PC
Location Two has 1 PC
Location Three has 2 PCs  (this is where the second router is)
I will try the solutions and let you know how it works as soon as possible, but I will not have access to the routers for about 3 hours.  If there are any other questions, just ask, I will keep watching this until I can try the solutions.
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cycle303Commented:
BTW, if you are only using the second router as a hub so to speak, I would connect router1 to one of the lan ports on router2.  I would make sure that DHCP is turned off on router 2.  This would make things easier to deal with.
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rcheneyAuthor Commented:
No matter what I do, both computers cabled to the first router work fine.
The second router works great with ONE computer, but as soon as I hook up the second computer, both of the computers (on the second router) disconnect from the network. The second router is connected from a LAN port on the first router to a LAN port on the second router.
==== specs below ====
first router (Linksys WRT54G)
Internet connection type = Automatic Configuration DHCP
Local IP = 192.168.1.1 (on setup page)
IP Address 24.245.39.82 (on status page)
DHCP Server = enable
Default Gateway = 24.245.39.82

second router
(Netgear MR814 version one)
========from status page=========
LAN Port
IP address = 192.168.1.201
DHCP = none

Internet Port
IP address = 0.0.0.0
DHCP = client
IP Subnet mask = none
Domain Name Server = none
====from basic settings page===
Internet IP Address = Get Dynamically from ISP
Gateway IP Address = 0.0.0.0
IP address = 0.0.0.0
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jasfoutCommented:
Router1 looks great...leave it alone now

In response to:
>>The second router works great with ONE computer, but as soon as I hook up the second computer, both of the computers (on the second router) disconnect from the network.

A few things come to mind:
1. Does it make a difference which computer on Router2 is hooked up 1st? or regardless of which machine is hooked up first...the first one works but when the second is hooked up they both go down?
(If it is only when a specific machine is hooked up I would suspect a faulty NIC or malware on it)

2. Are both computers hooked to Router2 setup to use DHCP? if not have you verified that they are using separate yet valid IP addresses?

It is also possible that you  have a bad cable or perhaps even a bad switch port on your router.  Have you tried swapping cables/ports?(This would follow along #1 above)

What is the Operating System of the machines connnected to Router2?
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rcheneyAuthor Commented:
I tried connecting to Router2's LAN port and disabling the DHCP on Router2, and it doesn't work, I think because Router2 has an IP address assigned by Router1, Router2 is then trying to send data back and forth on the *one* IP address from two separate IP addresses.  I also tried connecting Router1 to the Internet port of Router2 and then leaving the DCHP enabled and giving each router a separate IP address, the result was the same, everything works fine for awhile, sometimes for an hour, then one of the computers connected to Router2 disconnects from the network, sometimes they both disconnect.  If I unplug one of the computers from Router2 so that there is only one computer connected to Router2, it doesn't matter which computer, it works great and does not disconnect from the network.
=========questions answered below===========
1. Does it make a difference which computer on Router2 is hooked up 1st? or regardless of which machine is hooked up first...the first one works but when the second is hooked up they both go down?
(If it is only when a specific machine is hooked up I would suspect a faulty NIC or malware on it)
-------------
I am not by the network right now so I can't test to see if it makes a difference which computer on Router2 is hooked up 1st.  I *think* (but I'm not sure) that the second computer that connects tends to be the first to go offline, but eventually they both disconnect from the network.  Regarding the malware -  one of the computers connected to Router2 says "About Blank" in the address bar when it first loads, for two seconds and then the browser looks normal and goes to the Google home page.  I plan to scan that computer for the AboutBlank thing and get rid of it, until you mentioned it, it wasn't bothering me so I didn't deal with it.  I will test the order that they connect, etc., and report back.
--------------
2. Are both computers hooked to Router2 setup to use DHCP? if not have you verified that they are using separate yet valid IP addresses?
-------------------
How do I check to see if both computers hooked to Router2 are setup to use DHCP?  If that in the TCP/IP settings?  I will check that, and see if when both are connected and working, if they have different IP addresses.  When they disconnect, I can go to the LAN connection poperties and disable the connection, then re-enable, then "repair" to renew the IP address and then it sometimes reconnects to the network.
----------------------
It is also possible that you  have a bad cable or perhaps even a bad switch port on your router.  Have you tried swapping cables/ports?(This would follow along #1 above)
---------------------
I bought brand new cables just to be sure and I bought several different routers, Linksys, Netgear and Dynex, I tried different ports, etc.
-----------------
What is the Operating System of the machines connnected to Router2?
-----------------
XP Pro
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cycle303Commented:
Do not connect anything to router2 WAN port.  As long as DHCP is disabled on router 2, it should act as a switch.  Of course another simple solutions would be to pick up a cheap 5 port switch or hub.
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rcheneyAuthor Commented:
----pick up a cheap 5 port switch or hub.----
Switches need to be placed after a router, the cable modem and the first router are in the basement and Router #2 is on the second floor where I need wireless in addition to the two cabled computers.  That is why I am using two routers instead of a router followed by a switch.  The second router is supposed to act as a switch anyway.
Maybe each computer needs to have a static IP address?
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cycle303Commented:
Ohhh... Are you trying to setup a wireless bridge between the two routers?  This could be done differently.  Try this scenario out.  
Router 1
LAN --
IP - 192.168.1.1
mask 255.255.255.0
DHCP enabled

Router 2
-- Leave the wan port as DHCP connected to the LAN of router 1
LAN --
IP - 192.168.2.1
mask 255.255.255.0
DHCP enabled
---------------------------------------------------------------------------------------------
There can be problems with this setup as it seems that you have already encountered.  It is probably due to the fact that you are double Natng.  The other solution would be:
Router 1
IP - 192.168.1.1
mask 255.255.255.0
DHCP enabled
Make sure that your DHCP scope starts at least at 192.168.1.3

Router 2
WAN PORT - Disconnected
LAN connected to router 1 LAN
Router 2 IP - 192.168.1.2
mask 255.255.255.0
NO DHCP

This will cause your clients to receive a DHCP lease from router 1 with the correct gateway.  The problem will come when you connect wireless clients to router 2.  If you can configure router 2 in bridging mode properly, then all is well.  If not, you should manually assign IP's to wireless clients with router 1 as the gateway... EX
IP 192.168.1.50
mask 255.255.255.0
GW - 192.168.1.1
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rcheneyAuthor Commented:
Per the advice above, I will try to set Router #2 to "bridging".  
When you say, "manually assign IP's to wireless clients", do you mean -wired- clients, computers cabled to Router #2 ?
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jasfoutCommented:
I have my home network setup similarly as follows

ROUTER1
WAN connection to modem
LAN IP 192.168.1.1
DHCP Range 192.168.1.100 - 150

ROUTER2
WAN connection to ROUTER1 LAN port
WAN static IP 192.168.1.2
LAN IP 192.168.1.1
DHCP range 192.168.1.200 - 225


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jasfoutCommented:
ouch...sorry

should be:
ROUTER2
WAN connection to ROUTER1 LAN port
WAN static IP 192.168.1.2
LAN IP 192.168.1.3
DHCP range 192.168.1.200 - 225

misstated LAN IP
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cycle303Commented:
I think I am making this harder than what it needs to be.  You can utilize bridging on your router2, but I need to know what router 2 is in order to give you better direction on how to hook it up.  If it is a true bridge, then you would connect router1 LAN to router2 WAN and everything should work fine.  DHCP should pass from router1 through router2 to your clients.  Let me know what the model of the router is and I will tell you how it all will work.
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jasfoutCommented:
cycle303,
per comment above:
 Router2=Netgear MR814 version one
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rcheneyAuthor Commented:
IT WAS A VIRUS ! Thank You to everybody who contributed and helped with this crazy problem. The second computer kept disconnecting from the network because it had the "Worm:Win32/Allaple.A" virus.  I ran four different malware/antivirus programs on the computer and they didn't detect anything and then I downloaded the free malware program from Microsoft (http://www.microsoft.com/security/malwareremove/default.mspx) and it found the virus, removed it and everything worked fine after that.  You all deserve credit for the solution.
Thank you donjohnston for answering quickly and stepping through each of my initial questions and answering each question individually.  
Thank you cycle303 for the detailed explanation and specs for two different ways to set it up including which port to connect, etc.
Thank you jasfout for the concise specs with LAN and WAN IPs, DCHP ranges, etc., and for having an actual network with the same setup as my network providing a factual example and, most importantly, your questioning if maybe something else was wrong made me try swapping PC #2 for a different PC which ultimately lead to the discovery that PC #2 was the problem.
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jasfoutCommented:
For future reference...
If you turn on automatic updates, all critical updates will automatically be installed when released.  That malicious software tool was released back in 2005 and in my opinion is a necessity on all Microsoft machines.
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rcheneyAuthor Commented:
Thanks, it was my wife's PC, she's not a techie, and I didn't realize she didn't have automatic updates turned on, and her AVG Antivirus was not set to update automatically.  I fixed it now.
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