PPP over GSM modem working with every PC

[daniel.quack]

Hello,

maybe any of you experts can help me with the attached Microsoft Network Monitor capture files. The PPP connection between two GSM modems (Windows 7 to Windows 7 "server") is working fine. Another connection (Device-in-field to Windows 7 "server") is not working. The connection cannot be established due to a IP address exchange problem I think. Sorry for this short version, but this forum marks my detailed posting as spam -.-.

If you need any further information please answer!

[Georg Pauwen]

Hello Daniel,

the TCP DUP ACKs point to packet loss somewhere in the path. The 'Device-in-field' is a laptop I assume. What is the physical setup, what are the devices in the link between the field device and the Windows 7 server ?

[daniel.quack]

Thanks for you answer, gpauwen.

The device is a Node A by Commscope. It has an integrated SiemensHC25/Cinterion PHS8 UMTS/GSM Modem.

Additionally I can say, calling the NodeA from Windows7 (Windows7 -> NodeA) works, the connection can be established without problems.

But in the opposite direction (NodeA calling Windows7) is not working.

[Georg Pauwen]

Thanks for that additional information...I'll do some research...

[Georg Pauwen]

Hello,

hard to find any docs or manuals...

I guess the first thing to test would be to turn off the Windows firewall, and to disable any virus scanners active on the system.

What is connected on the Windows 7 side ? A modem ?

[daniel.quack]

Yeah i know, I did also find nothing useful.

On the windows side there is a WAVECOM MODEM MULTIBAND 900E 1800 connected, at serial port.

My latest idea was to disable the compression mode that windows wants to use and the NodeA declines (looks like the connection gets stuck at the "CCP" point). But i don't get compression disabled, the setting in the device manager is grayed out.

[daniel.quack]

I think i got the solution!

In settings of the incoming connection in Windows7 I had to uncheck the "All users must save their credentials" (dont know the exact english text) on the tab "User". After unchecking this the connection could be established successfully

[Georg Pauwen · Accepted solution]

Daniel,

good stuff ! Honestly I don't see a relation between the Wireshark output and that Windows setting, but if it works, it works !

[daniel.quack]

Exactly, I dont understand what the IPCP/CCP procedure has to do with this user setting, but with checked it produces exactly these 27 lines of conn-setup, without it works. Tested it a few times. As so often, trial and error worked :)

Anyways thanks for your help!