I installed osmc on RPi2B and had no problem with playing movies from usb-disk.
week ago I set SMB on my router Synology RT2600ac and changed library from usb-disk to smb.
from that moment every movie I wanna play after few mins start buffering.
RPi2B is hard wired to router and hdmi wired to TV.
have you maybe any ideas how to solve that?
I forgot to add that watching movies on laptop (wireless) has no issues.
Routers typically make horrible file servers. You could go back to usb-disk to smb connected on the Pi and then enable Samba Server from the MyOSMC app store to share the contents to other devices on your network if that is what you are trying to achieve.