I have created 3 DreamHost servers running CentOS 6.7, A, B and C. I can sftp files of any size from between servers A and B. I cannot sftp a file larger than 1000 bytes from C to server A or server B. I can sftp a file of any size from server C to a local Ubuntu machine. Any suggestions?
I found out that the issue was MTU size. The default MTU size of the machines created are 8900. That seems to fail sometimes. I set it to 1400 and my sftp now works for servers A, B and C.