ECE/CER Flags

I am trying to connect to a customers SFTP via C# Code, When I run the console app from my local PC it works fine, when I deploy it to Azure it fails, The logs are saying

. 2018-09-12 04:06:51.022 Server offered these authentication methods: publickey,password
. 2018-09-12 04:06:51.475 Offered public key
! 2018-09-12 04:06:52.103 Server refused our key
. 2018-09-12 04:06:52.725 Server refused our key
. 2018-09-12 04:06:52.725 Server offered these authentication methods: publickey,password
. 2018-09-12 04:06:53.178 Prompt (password, "SSH password", <no instructions>, "&Password: ")
. 2018-09-12 04:06:53.859 Disconnected: Unable to authenticate
. 2018-09-12 04:06:58.933 Failed to connect to <IP>: Network error: Connection timed out
. 2018-09-12 04:06:58.933 Knocking FTP port.
. 2018-09-12 04:07:00.960 FTP port did not open.

I can log on with WinSCP UI and transfer no problem. The It Guys that side say that
The first two SYN packages have ECE and CWR flags enabled. These are apparently a new extension to TCP for congestion management. I suspect that their appearance is poisoning the network stack and host firewall states. It would be preferable if that feature could be disabled.

ANy help in this would be appreciated

I do not see why this should have anything to do with TCP/IP flags.
TCP/IP connection obviously succeeded. It's an SSH authentication that is failing.
When you write that "I can log on with WinSCP UI and transfer no problem." - Do you mean that you can login from Azure machine? Show us a full log file for that. And also full log file from your C# session.

martin wrote:

I do not see why this should have anything to do with TCP/IP flags.
TCP/IP connection obviously succeeded. It's an SSH authentication that is failing.
When you write that "I can log on with WinSCP UI and transfer no problem." - Do you mean that you can login from Azure machine? Show us a full log file for that. And also full log file from your C# session.

I can log on from my laptop running Windows 10 and the download works, as soon as I run from Azure it fails. After I posted this message it did run successfully from Azure but just once so I suspect its something on the Server side

Can you connect from Azure using any other SSH/SFTP client?