How do I discover or reset the password

If you do not have a router you have to reboot the modem first, Modems pair with one device at a time using its MAC address, using a router allows you to add remove computers to your internet access without rebooting the router for every device because the modem pairs to the router and the router shares its internet with your other devices.

Hi. Sometimes, you have to contact your internet provider, and they have to send an initialization string to the device in order for it to get internet.
Also, check the settings of your router and make sure it is set to allow internet access, and not just router access. They can be tempermental sometimes.

Does the 5100b not have a "pingable" option? Or something about allowing WAN ping?
You might have to go into the advanced options or whatever to find the option to allow pings.

I solved this problem, by hitting the reset button on the bottom of the modem, now I have no problems

My son went on the computer and reset the modem to the computer.

Turns out that the modem stopped transmitting a wireless connection so that is why we couldnt get it working. After nearly putting a hammer through the laptops, we decided that we had better buy another modem. It now works better than ever :-) (phew)

you can't.
when the item name as modem/router. it means the main function is modem with added router function.
you can't connect 2 router/modem together. both need access to the internet and IPS for it function correctly.
however, you can connect 1 modem and one router.

401 Authorization Required is the message you get after the default allowed password attempts have failed. When trying to access the Speedstream, you didn't type in the correct password which results in that failure message.

I have just set up 4200 with dsl - you may find that you need to reset modem before you can configure. I was told that you need either a grey or yellow cable from your laptop to the modem. I use 10.0.0.138 to access modem. The 4200 I have was from a bigpond a/c - originally configured accordingly.
Regards,
Richard

Symptoms * You have a new router, and cannot get online to the Internet. AND * The Setupwizard will detect dynamic IP even though you have a PPoE connection. (Going to router status on the administration page, there is a private IP address on Internet port. 192.168.x.x range.) Cause The SBC DSL modem SpeedStream 5100b, used on new DSL and Yahoo SBC DSL installations since Feb. 2004, causes the NETGEAR router Setup Wizards to fail, and prevents routers from connecting to the Internet. This problem affects many router brands. The modem can be distinguished from the earlier 5100 by a 5th light labeled "Internet". The SpeedStream 5100b's default configuration is "PPPoE on the Modem" ? matching a built-in PPPoE client convenience feature that sends login ID and password to SBC. To Work Around These Issues, Configure the Modem for Bridged Mode Note: In Bridge Mode you cannot to connect to the modem's configuration menu, except by resetting it as described below. 1. Disconnect the router from your network, and connect the computer directly to the SpeedStream modem 2. Open an Internet browser. 3. Type 192.168.0.1 in the browser address field and click Enter. The modem displays a configuration menu. 4. Click Advanced. 5. Enter the "Access Code" printed on the bottom of the modem. 6. Click PPP Location. The PPP Location screen appears. 7. Select Bridged Mode (PPPoE is Not Used). 8. Click Save Changes. 9. Connect the router between the computer and the modem. 10. Power off the modem. 11. Power off the computer. 12. Connect the Internet port of the NETGEAR router to the Ethernet port of the modem. 13. Connect the computer to a LAN port on the NETGEAR router. 14. Power on the modem and wait for 2 minutes. Don't go to the next step until this is finished. 15. Power on the router and wait for 1 minute. Don't go to the next step until this is finished. 16. Power on the computer. 17. Log in to the router by typing 192.168.0.1 in your browser. 18. When prompted, using lowercase letters, type admin for the user name, and password for the password. Some older routers use 1234 for the default password. If you forgot your router password see http://www.fixya.com/ThreadView.aspx?thid=102081&prdid=252188 19. Use the Setup Wizard to connect to the Internet. To Reset the Modem To Enable Access to the Configuration Screen 1. Disconnect the computer from the modem. 2. Power off the modem. 3. Power off the computer. 4. Connect the Ethernet port of the modem to the computer Ethernet port. 5. Power on the modem and wait for 2 minutes. Don't go to the next step until this is finished. 6. Power on the router and wait for 1 minute. Don't go to the next step until this is finished. 7. Power on the computer. 8. Open an Internet browser. 9. Type 192.168.0.1 in the browser address field and click Enter. The modem displays a configuration menu. 10. Click Advanced. 11. Enter the "Access Code" printed on the bottom of the modem. 12. Click PPP Location. The PPP Location screen appears. 13. Select PPPoE on the modem. 14. Click Save Changes. 15. At the login screen type in your SBC member ID and password (which is usually the primary email address on the SBC DSL account and the password for the primary email address). 16. Click Connect. * If successful, a screen appears reading "You Are Connected", and the Internet light goes solid green. * An error will display if the username or password is invalid. * If there are other problems the message "The DSL connection is down" appears.