I have two TVs with kodi installed and a fileserver on the same LAN network.
I used kodi to map the same path in the file server to the same name but trakt still don't update the watch database from these devices
This usually means the sync settings aren’t turn on in both plugin settings. Take a look at http://blog.trakt.tv/kodi-scrobbler-sync-plugin-1f148b5070a5 which has a screenshot of what those settings look like. Also note that a sync is triggered after a library update so you might need to set that up to run periodically.