Efficient → Re: Speedstream 5667 - Need To Change Back To Router Mode

Normally a part number 060-5667-001 is a Bridge Only unless a ISP field upgraded the Firmware. Did your 5667 come from Earthlink? If yes, Earthlink only supplied 5667 Bridge versions. The Router versions are:

060-5667-0xx = Modems (rare exception - Frontier ISP in-house upgraded some units to Routers with special flash file 060-5667-010)
060-5667-101 = Router/Bridge (South America issue only)
060-5667-501 = Router
060-5667-507 = Router

Your Firmware version R3.1.0 is a Bridge Firmware only as seen here.

»5667 Bridge Console + xmodem + Firmware revisted..

Hi Doc. Thanks for the info. The modem originally came from Centurylink in eastern Washington state back in 2001. I remember it having a working web UI, NAT, and DHCP when I first got it before I switched it over to Bridge mode. So, there's no way to switch it back?

If it has Router Firmware, then it will have a Web Interface to access to change it from RFC2684 (aka Bridge Mode) back to Router Mode PPPoA/PPPoE. Set your Ethernet card to a Static IP in the range the Modem uses and then reboot to make sure the PC settings take. Then use your Browser to access the Web Interface. That's where you change Modes between a Router and a Bridge.