SFTP Transfers stall

[klam0]

When transfering files (downloads) sometimes it just stalls, there is no progress in the Filezilla client anymore. I got the following two cases from the Message Log in verbose mode:

11:44:28	Trace:	CSftpChangeDirOpData::ParseResponse() in state 2
11:44:28	Trace:	CControlSocket::ResetOperation(0)
11:44:28	Trace:	CSftpChangeDirOpData::Reset(0) in state 2
11:44:28	Trace:	CSftpFileTransferOpData::SubcommandResult(0) in state 1
11:44:28	Trace:	CSftpControlSocket::SetAsyncRequestReply
11:44:28	Trace:	CControlSocket::SendNextCommand()
11:44:28	Trace:	CSftpFileTransferOpData::Send() in state 4
11:44:28	Command:	reget "file" "X:\file"
11:44:28	Command:	remote:/file => local:X:\file
11:46:47	Trace:	Network error: Software caused connection abort
11:46:47	Trace:	Got eof from child process
11:46:48	Trace:	CControlSocket::ResetOperation(66)
11:46:48	Trace:	CSftpFileTransferOpData::Reset(66) in state 4
11:46:48	Error:	File transfer failed after transferring 27,262,976 bytes in 139 seconds
11:46:48	Trace:	Could not read from child process with error 4, raw error 109
---
16:11:31	Trace:	CSftpConnectOpData::ParseResponse() in state 3
16:11:31	Trace:	CControlSocket::ResetOperation(66)
16:11:31	Trace:	CSftpConnectOpData::Reset(66) in state 3
16:11:31	Trace:	CControlSocket::ResetOperation(66)
16:11:31	Trace:	CSftpFileTransferOpData::Reset(66) in state 0
16:11:31	Error:	File transfer failed
16:11:31	Trace:	CControlSocket::SendNextCommand()
16:11:31	Trace:	CSftpConnectOpData::Send() in state 0
16:11:31	Status:	Connecting to x.com:22...
16:11:31	Trace:	Going to execute C:\Program Files\FileZilla FTP Client\fzsftp.exe
16:11:31	Response:	fzSftp started, protocol_version=11
16:11:31	Trace:	CSftpConnectOpData::ParseResponse() in state 0
16:11:31	Trace:	CControlSocket::SendNextCommand()
16:11:31	Trace:	CSftpConnectOpData::Send() in state 3
16:11:31	Command:	open "x@x.com" 22
16:11:31	Trace:	Looking up host "x.com" for SSH connection
16:11:31	Trace:	Could not read from child process with error 4, raw error 109

Both end with this line "Could not read from child process with error 4, raw error 109". Stopping or starting the process queue has no effect anymore.

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