NW6SP5 BM38Sp2

I have just configured BM as an ftp reverse proxy for a NW6.5SP5 ftp server.
When I ftp a large file through the proxy and I get to 34,276,096 bytes it
disconnects me with the following:-

ftp: get :Connection reset by peer

If I conncet directly to the ftp server and do the same, I can pull down
the whole file.

Can anyone help Please ?