Also just been through an issue of losing connection - what was happening was Expedition was restarting and connection settings were reverting to disabled.  Version 1.40 firmware, tried mode forced to N2K and RAW same issue.
For my resolution, I went into Yacht Devices settings, unchecked all the N2K PGN, then added GPS only - was stable, then checked only the ones I needed to receive.  Has been faultless since.  I have not found which specific PGN selected caused mine to fall over.  This information may help in your case!