Thanks for the posts fzinken / jzimmer. I have Vero 4k boxes, but none of the media is anywhere near that resolution. Most is 720. I may have the odd thing at 1080. The films I have range in size from 800MB to 2GB. Once the media starts playing I get zero lag or artifacts. If I am reading the iperf figures right I am able to transfer about 56Mbit/sec which is 7MB/s. The biggest film would be in the region of 2GB and 1hr 40mins. So thats 6,000 seconds and 2,000MB, which has a bandwidth requirement of way less than 1MB/s. Please let me know if I have misunderstood this. There is no lag when running the media from the box it is directly connected to, and the initial time to start playing lag seems proportional to the size of the media file when accessing it from the second box. This seems to me to be perhaps that the second box is isnt starting to play the media straight away. Is it buffering an amount of the media, or is this something to do with the connection being set up as SFTP and possible encryption overhead?
I havent been able to get the FTP connection set up because of the aforementioned messages I get and havent had a chance yet to work through the process of setting up the NFS connection; I hadnt realised I needed to install additional software on the box to achieve this.