Lost Installation CD for WRT54G version 5

Question

Hi,
I have been using Linksys wireless router WRT54G V 5. I decided to change Internet service provider last week. It used to be starhub maxonline (cable modem) now I changed plan and use singtel broadband( ADSL modem)
My way of connection is this. From cable modem to wireless router. And Wireless Router direct out to a PC via ethernet cable. And I have a laptop in another room which is on the internet wireless.  In short, 2 terminal. One direct terminal and One wireless terminal.
When I disconnect the old modem(Cable) from the router and connect with the new modem(ADSL),  it is not working.  Even the direct terminal is not working.
Why is this so? There is nothing wrong with the ADSL modem as I plug it in directly, it is working.
I believe I need the installation CD? If so, where can I download this? I have lost it.
Please reply to my message. Thanks alot
Can reply through my email at [email protected] or reply here too.
Thanks!

Answer 1

Well, not quite. But you have posted the bit of information which reveals a little bit about the modem: your modem is not a simple modem but also a router. It runs on 192.168.1.254 and has a DHCP server. Now your Linksys router uses the same IP address subnet 192.168.1.* for its own LAN. A router which is connected to the identical subnet on the internet/WAN side and the LAN side cannot work because it cannot route. It never knows where to send a packet for 192.168.1.*.
O.K. The quick solution is: wire a computer to a numbered LAN port of the router. Do not connect the modem to the router. Open http://192.168.1.1/ no username required, default password is "admin". On the setup tab change the LAN IP address of the router from 192.168.1.1 to 192.168.2.1. Save the settings. The router will reboot and the computer will loose the connection. That's O.K.
Wire the internet port of the Linksys to the modem. Reboot the computer. The computer should now have an IP address like 192.168.2.100 in ipconfig. You can open the router configuration at http://192.168.2.1/
Internet should work now.
What you did then, you have chained two routers. The Linksys LAN uses 192.168.2.*. The modem/router LAN uses 192.168.1.*.
There are certain disadvantages of this setup. It may slow the connection down a little as everything goes an additional hop. You cannot use some functions on the Linksys like DDNS as those require a direct connection of the Linksys to the internet (which is not the case, the modem/router has the internet connection and shares it with the Linksys). Other things like port forwarding (for online games or similar) get more complicated because you have two routers in chain on which you have to configure the port forwarding.
I would rather recommend either of these two options:
1. Put the modem/router into "bridge" mode. In bridge mode you turn off the whole router part. Now the Linksys is able to access your ISP directly. You'll probably have to configure your Linksys for PPPoE (you can currently see what you need in the modem/router) with username and password.
2. Set up the WRT as access point only. Then the modem/router is your internet gateway router. All internet functions have to be configured on the modem/router only. To set up the WRT as access point see here.
And: don't forget to secure your router! see here.