Thank you for the reply.
I am streaming over the LAN and already tried changing the ports and cables. The same DVDs can stream normally to my Windows PC, again using Kodi with no issues. I seem to be getting the same cache drain issue when I stream to my OpenElec Rpi2 box which is consistent with the 100Mbit and relatively small RAM pool being the root cause. however I see advancedsettings.xml have no impact whatsoever regardless of what values I put in there for cache.
I tried the LE 7.9 alpha and the buffering was not seen in Kodi 17 there however video playback was very poor and the sound would disappear after a few seconds of play time.