Two different router IPs in the same network

norroy

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Feb 20, 2014
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Hi guys

I have been struggling with a problem I couldn't solve using various forum threads and google searches. I installed a "new" router (Linksys Wireless-G ADSL Home Gateway). Everything works perfectly with my laptop. My roommates laptop can connect to the network. However, it can't get a connection to the internet. Here's the situation:

According to my laptop, the IP of the router is 77.xx.xx.x.

According to my roommates laptop, the IP of the router is 192.xxx.x.x. The weird thing is, his laptop responds perfectly to ping with that IP. My laptop fails to ping that IP.

I really can't get my head around this situation, I hope you can help me.
 
Solution
You need to provide more details. How many routers in your building? Where does the Internet connection come in on? Does it come in a modem? If so, which router is the modem connected to? If the Internet comes in on a combination modem/router, how many routers are there in addition to this one? How much of this is wired and how much wireless?

It's hard to troubleshoot your issues without knowing exactly what devices you have and how they're connected.

By the way, each building or location is usually assigned just one Internet addess (IP address). The router gets this address, typically of the type 77.xx.xx.xx. However, routers usually provide network address translation (NAT). What this means is that they assign non-routable...

COLGeek

Cybernaut
Moderator
The 77.x.x.x address is the router's external address (the one the rest of the internet sees). The 192.x.x.x addresses are internal addresses for your connected devices. Typically, your router's internal address is something like 192.168.1.1 and that is the gateway address that is used by connected devices to connect to the 'Net. Does your router have DHCP enabled?
 

mbreslin1954

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You need to provide more details. How many routers in your building? Where does the Internet connection come in on? Does it come in a modem? If so, which router is the modem connected to? If the Internet comes in on a combination modem/router, how many routers are there in addition to this one? How much of this is wired and how much wireless?

It's hard to troubleshoot your issues without knowing exactly what devices you have and how they're connected.

By the way, each building or location is usually assigned just one Internet addess (IP address). The router gets this address, typically of the type 77.xx.xx.xx. However, routers usually provide network address translation (NAT). What this means is that they assign non-routable IP addresses to devices connected to them, such as 192.168.x.xxx, or 10.x.x.x. These two examples are non-routable address ranges, which means they are not used on the actual Internet. So all devices connected to the router share the real, actual IP address, and internally, amongst themselves, they use one of the non-routable addresses. The router keeps track of which packets coming from the Internet to it's one IP address go to which device connected to it.

Here's an explanation of NAT:

http://en.wikipedia.org/wiki/Network_address_translation
 
Solution

norroy

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Feb 20, 2014
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Thanks for your reply.

The Internet comes in through a combined modem/router (Thomson TWG 870) which is in bridge mode (Legacy RG IPv4 Mode disabled and WiFi turned off). The Linksys-router is wired to the Thomson device.

I hope this is enough information
 

mbreslin1954

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So I take it both yours and your roomate's latops are connected to the Linksys router?

Here's what I think I understand, correct me if I'm mistaken:

1) Your laptop connects to the Internet without any problem.
2) His laptop cannot get to the Internet

(I'm not sure why IPv4 is disabled, everyone uses it, you can't really use IPv6 until all devices on the Internet support it)

What do you mean when you say that "his laptop responds perfectly to ping with that IP". Who's pinging whom?

What is your IP address? Don't worry about divulging it, if it's 192.xxx.xxx.xxx, most people in the world have that, as do I at my home. It's non-routable.

Have you connected to the Linksys' webpage and configured it? If not, what model is it?
 

norroy

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Feb 20, 2014
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IPv4 is only disabled on the combined router/modem to enable the bridge mode (the inbuilt router off the modem is to weak to reach the whole apartment, thats why I'm using the Linksys device)

My laptop connects perfectly, my IP is 77.xx.xx.x. I can't ping 192.168.1.1
My roomates laptop can't connect to the Internet, according to his laptop the IP of the router is 192.168.1.1. He is able to ping this IP.

The only thing I have configured is setting a personal WPA2 encoding of the Linksys router.
 

mbreslin1954

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Your problem is that YOU have obtained the building/room's IP address. In effect you have a one-user Internet connection, and you've got it. Your roommate and anyone else wanting to use it is out of luck.

It sounds like your router is not doing any routing, it is totally passive. You need to connect to it and set it up.

 

mbreslin1954

Distinguished
Your router is passing on the modem's IP address to you.

Do you have the manual for the router? If not, google the brand and model number and you can download it. Search for something like "Linksys 48RGT manual".

The directions will tell you what to do. If for some reason you can't find the manual, tell me the model number and I'll tell you how to configure it.
 

norroy

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Feb 20, 2014
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The model number of the router is Linksys WAG200G Annex-A. Even though i found a manual i can't really figure out what to do next. I'd be glad if you could help me
 

mbreslin1954

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Here's what I think is your manual. Can you look at the first few pages and confirm that this is your device?

http://www.avc.com.hr/eurostar/Artikli/DVR/Router/LinkSys/WAG200G_manuals.pdf

Do you have the CD-ROM that came with the device? They recommend disconnecting the router from everything except an Ethernet cable connected to your PC, then running that Setup CD. Let me know if you can do that (i.e., do you have a wired Ethernet port on your laptop, do you have a cable, etc.).
 

mbreslin1954

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They also make this statement in the manual, at the very beginning:

"If you have a modem connected to your network, disconnect it. The Gateway replaces your modem."

Assuming you have a DSL Internet connection, this sounds to me like they want you to connect the DSL cable directly into the router, you don't need the modem in the picture at all.
 

norroy

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Feb 20, 2014
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This is the router. I don't have the CD-ROM (I couldn't use it anyway since I'm using a Mac). But I can access the web-based setup-page via Ethernet cable.

I do have DSL Internet, but the problem is I simply can't connect the cable directly to the Linksys device, I do need the modem...
 

mbreslin1954

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Why do you need the modem? The Linksys has a modem in it. It expects to receive the DSL cable in the white port on the back labeled "LINE". I don't know how to make it work if it doesn't receive a DSL line into it. It's not a generic router, as are most on the consumer market, which take a standard Ethernet port as input.

I think you have purchased the wrong type of device. You already have a modem, which you say that you need to use, so go out and buy a standard Ethernet router, not one with a built-in DSL modem in it.
 

mbreslin1954

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Perhaps I was too hasty in my last post. Since your Linksys IS a router, it's possible that by plugging the output of your modem into one of the yellow Ethernet LAN ports on the Linksys, that you might be able to set up the Linksys as a router. I would try that by connecting to the router when it is not connected to anything, and set it's WAN (wide area network), or Internet address, to the one you are getting now (77.xx.xx.xx). It's possible that the Linksys will grab that when it boots up (if it's first connected to the modem), since you will have programmed it to do that, then, when laptops connect to it, like yours and your roommate's, you will get a NAT address (192.168.xxx.xxx). But when you connect to the Linksys to set it up, make sure that DHCP is turned ON (it sounds like it's already on). And make sure the Linksys has it's own LAN address set to 192.168.1.1. By common standard, the first address in a range is always that of the router.