Wired magazine has called Error 678 "the 666 of DSL users". It is sometimes easy to solve, but there are certain cases that have no resolution except to use a router, or even re-install Windows XP.
Here are troubleshooting steps to try first:
Recreate your connection
- If you are using Windows XP, Vista try a TCP/IP reset. This can be done like so:
- Click START
- Click run
- Type the following in the box: netsh int ip reset reset.log
- Click OK
- You will notice a box pop up for a couple of seconds, then vanish. Restart your computer and try again.
- Make sure the modem has sync (look for the light labeled line sync, SYN, or ADSL link)
- Make sure the modem is connected to the computer properly
- Try powering down both the computer and modem for a minute or two.