Bridging the 4200/5200 Router
***Official Disclaimer***
Neither I nor Alltel/Windstream/Your ISP/Anyone else will be held accountable for what you or anyone else does inside your router or on your computer or any software you download and/or install. If you change/remove/corrupt something up on your computer or router or equipment and someone has to fix it or replace it for you and charge you money/services/beer for fixing it then it's your responsibility not mine nor is it Alltel/Windstream's or your ISP's or anyone else's. I give you the information that I have learned/found/acquired. What you do with it is up to you. Do not email me with questions or complaints about why your router/computer/equipment/etc. doesn't work. I cannot guarantee that this config or these settings or information on this site will work for everyone. I can't test all solutions possible because I don't know them all and there are not enough hours in the day/week/month/year for me to test every combination possible. I have tested/used these configurations/software and they work for me. I am just letting my findings be open to help others in times of need at no cost. If you do not understand these instructions/configurations/software or are afraid that you will mess up the computer/router/equipment/software then you will want to contact a computer/network technician to help fix/configure/build what you need done.
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In order to turn the 4200/5200 router into a bridge I usually just remove all the VC's and create just a bridge connection. This will of course require you to log into the 4200/5200 via it's web interface http://192.168.254.254 is the default web interface. Username and password are by default set to admin and admin. Once into the 4200/5200 web interface you may have to login again by clicking on the Login link on the left side. It will then bring up a screen that shows username as admin.. password will also be admin. Either way, once you are logged in to the router and see Setup on the left side then proceed with the steps below to bridge your router. As a note, I am assuming that you are setting up the bridge for a PPPoE connection. Other types of connection may require different steps in order to connect.

Some versions of the 4200/5200 router may have a "Bridge" option, I advise against using that because if you should decide to return your 4200/5200 back to a router you will either have to buy a new router upgrade from Speedstream or get in contact with your ISP. The way that I show you here will allow you to go back in and re-setup the 4200/5200 as a router again.
Once you are logged into the 4200/5200 click on Setup then WAN Interface
Now you should have screen showing all your VC's. To make things simple we will just delete all of them by clicking on the delete buttons on the right side.
Once we clear all these out we will create a new bridge from scratch. Just click on the Add A New VC button to begin the process.
On the first page we have to make sure that we have the correct VPI/VCI. For Alltel we would use VPI 0 VCI 35, other ISP's may use others. For encapulation type PPPoE will use LLC and the Traffic Class will stay as Unspecified Bit Rate and then click on the Next button.
For the protocol just select PPPoE and then hit the NEXT button.
Next we are going to select the Bridge only option and then hit the NEXT button.
On this page be sure to unselect all options and to disable NAT/NAPT then click on the NEXT button.
This pages just asks for what you want to call the connection, Just leave it as it is and hit the NEXT button.
Now on this last page you will be given the current VC's listed which should now be just OE BRG, now click on the FINISH button.
Now you should be back to the VC profile screen, don't reboot just yet. The next step is turning of the firewall and the DHCP server in the router so you don't have multiple DHCP servers on your network or a firewall blocking ports.
To turn off the firewall simply click on the Firewall link, then click on level. Then if it says the Current Level as anything other than OFF, just click on the Apply button and it defaults to turning the firewall off.
Now that you've made sure that the firewall is turned off click on the DHCP link on the left side and then select the disable option. Once you've disabled the DHCP server just click on the SAVE SETTNGS button and the next page will give you a REBOOT button, this will reboot your 4200/5200. Once the 4200/5200 has rebooted you will now have a 4200/5200 bridge.
You now have your Speedstream 4200/5200 successfully converted to a bridge. From here on out just make sure you setup your other router to a PPPoE connection and if it has the option for connect on demand or keep alive choose the keep alive option. If you do need to get back into your speedstream to set it back up as a router, you can still go to the 192.168.254.254 address but you'll have to hardcode your machine to a 192.168.254.xxx address first.

If you need to convert this back to a router I've provided instructions HERE