Windows XP SP2
While working on a client's system, every time they would try to make a dial-up connection, it went like this:
- Modem would pick up the phone and dial.
- Carrier sounds / handshaking would occur.
- Username and password were checked and verified.
- Then it would disconnect with an error code of "720"
More on the message:
Error 720 - the connection attempt failed because your computer and the remote computer could not agree on PPP control protocol.
I had tried every fix I could find. Removing the Winsock and Winsock2 keys, re-installing TCP/IP, and running a series of commands using the "netsh" tool.
None of that worked.
What seemed to work:
"WAN Miniport (IP)" seemed to be messed up some how. It was listed twice in Device Manager.
I had to remove the keys for the two entries from the registry, then I could remove the devices from Device Manager.
I had to use the "devcon" command to re-install the "WAN Miniport (IP)" device.
The command to restore the WAN Miniport (IP) device was:
devcon.exe install %windir%\inf\netrasa.inf MS_NdisWanIp
You can get DEVCON.EXE (32-bit and 64-bit) from here:
http://support.microsoft.com/kb/311272/
You can get more info on this from here:
http://www.daniweb.com/forums/thread18016.html