After windows creator update, I got exactly the same issue, every exactly 5 exact minutes, the stream stop, buffer for 2 second and start again from 2 seconds before the stop, that for every single movie, file format, and never ever had an issue with videostream to cast even 6Gb files, now it struggles with that issue even with 350mb 45minutes videos.
The 5 exact minutes it's also an indicator that maybe it isn't the connection or my pc problem but some bug introduced with windows update.
Thanks for helping.