Testing MCX455A bandwidth between Dell servers

I am testing MCX455A bandwidth between Dell servers using the commands:

Server: Ib_write-bw –d mlx5_0  –i  1 –a –F
and

Client: Ib_write-bw –d mlx5_0  –i  1 –a –F  <server address>

The results looks fine until # bytes = 65536

Then I get the message:

mlx5: usb1 : got completion with errors

00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000

00000000 00008813 08000029 40807dd3

Problems with warm up

This test used to work to completion and I don't think I've changed the configuration.  I have the same problem with multiple cards (I have 13).