I am seeing this same issue using Emby for Kodi on the Firestick.  I am using direct paths playback and seeing it freeze every 30-60 seconds on multiple firesticks.  I confirmed that playback was fine using the Emby app on my phone.  This started within the last few days (I believe it worked with no issues on Friday).  I am attaching both the Kodi and Emby logs in case that helps.  Let me know if there's anything else I should try. embyserver.txt kodi.log