Videos are buffering when reaching the last 5 minutes

Hello,

Here is my setup :
Plex media server (1.4.3.3433) running on a Synology 915+
I play my video on an apple TV 4.

For example if I watch a video which is about 40 minutes long, I can watch the video 35 minutes without failure or buffering...
And every time I reach those last 5 minutes, the videos stops every 10-15 seconds and the video is buffering... Once this done 5-6 times in a row, the plex media player (or server) skip the videos and plays the next, or stop it eventually.

The logs are attached.

Thanks a lot