The multipart data seems corrupted in some cases (test case attached):
The data being attached is a byte array filled with X characters. Notice the random data between the XXXXX and --boundary. I tested this uploading from a Windows system to a Linux server running nc -l -p 12000 connected by 100 Mbit ethernet switch.
The corruption does not occur uploading from a Linux system to localhost. I have attached the data that was received in binary and also as a xxd hex dump.