I have a QNX 7 machine with dual Intel NIC cards in it only 1 of which is plugged in. 

Transferring files from this machine is incredibly slow but sending files is lightning fast.  I have another older QNX 6
 machine (different NIC hardware) on the same network and transferring files in both directions is fine.

QNX 6 Machine:
C:\Users\admin\transfer>ftp 172.27.12.103
Connected to 172.27.12.103.
220 172.27.12.103 FTP server ready.
502 Unknown command UTF8.
User (172.27.12.103:(none)): root
331 Password required for root.
Password:
230-
    Welcome to QNX Neutrino!
230 User root logged in.
ftp> bin
200 Type set to I.
ftp> put deviceMgr.core
200 PORT command successful.
150 Opening BINARY mode data connection for 'deviceMgr.core'.
226 Transfer complete.
ftp: 11628544 bytes sent in 0.38Seconds 31009.45Kbytes/sec.
ftp> get deviceMgr.core
200 PORT command successful.
150 Opening BINARY mode data connection for 'deviceMgr.core' (11628544 bytes).
226 Transfer complete.
ftp: 11628544 bytes received in 0.66Seconds 17726.44Kbytes/sec.
ftp>

QNX 7 machine
C:\Users\admin\transfer>ftp 172.27.12.3
Connected to 172.27.12.3.
220 172.27.12.3 FTP server (QNXNTO-ftpd 20081216) ready.
502 Unknown command 'UTF8'.
User (172.27.12.3:(none)): qnxuser
331 User qnxuser accepted, provide password for qnxuser@SurfaceController.
Password:
230-No directory! Logging in with home=/
230 User qnxuser logged in.
ftp> cd /tmp
250 CWD command successful.
ftp> bin
200 Type set to I.
ftp> put deviceMgr.core
200 PORT command successful.
150 Opening BINARY mode data connection for 'deviceMgr.core'.
226 Transfer complete.
ftp: 11628544 bytes sent in 0.38Seconds 31009.45Kbytes/sec.
ftp> get deviceMgr.core
200 PORT command successful.
150 Opening BINARY mode data connection for 'deviceMgr.core' (11628544 bytes).
226 Transfer complete.
ftp: 11628544 bytes received in 73.31Seconds 158.62Kbytes/sec.
ftp>

Note that incredibly slow transfer rate!

I start networking to use just 1 NIC with a static IP
io-pkt-v6-hc -d e1000 &
if_up -r 10 -p wm1
ifconfig wm0 up
ifconfig wm1 172.27.12.3 up
inetd &

Ifconfig reports:
# ifconfig -a
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 33192
        inet 127.0.0.1 netmask 0xff000000
        inet6 ::1 prefixlen 128
        inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1
wm0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        capabilities rx=1f<IP4CSUM,TCP4CSUM,UDP4CSUM,TCP6CSUM,UDP6CSUM>
        capabilities tx=7f<IP4CSUM,TCP4CSUM,UDP4CSUM,TCP6CSUM,UDP6CSUM,TSO4,TSO6>
        enabled=0
        address: 00:0b:ab:d6:bd:15
        media: Ethernet none
        inet6 fe80::20b:abff:fed6:bd15%wm0 prefixlen 64 scopeid 0x11
wm1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        capabilities rx=1f<IP4CSUM,TCP4CSUM,UDP4CSUM,TCP6CSUM,UDP6CSUM>
        capabilities tx=7f<IP4CSUM,TCP4CSUM,UDP4CSUM,TCP6CSUM,UDP6CSUM,TSO4,TSO6>
        enabled=0
        address: 00:0b:ab:d6:bd:16
        media: Ethernet autoselect (1000baseT full-duplex,flowcontrol,rxpause,txpause)
        status: active
        inet 172.27.12.3 netmask 0xffff0000 broadcast 172.27.255.255
        inet6 fe80::20b:abff:fed6:bd16%wm1 prefixlen 64 scopeid 0x12


Nicinfo looks fine (gigabit, full duplex, no physical medium errors)
# nicinfo
wm0:
  INTEL PRO/1000 Gigabit (Copper) Ethernet Controller

  Link is DOWN

  Physical Node ID ........................... 000BAB D6BD15
  Current Physical Node ID ................... 000BAB D6BD15
  Current Operation Rate ..................... Unknown
  Active Interface Type ...................... MII
    Active PHY address ....................... 2
  Maximum Transmittable data Unit ............ 1500
  Maximum Receivable data Unit ............... 1500
  Hardware Interrupt ......................... 0x102
  Memory Aperture...