Try copying it first to the local drive (My Documents, etc)
Sometimes when the connection is not good, the default setting for network caching in VLC is not enough that it often stops and buffers for a while.
Go to Tools > Preferences > Show All Settings
Search for ‘caching’, click to open the Input/Codecs settings and look for network caching,
then set the value to 5000ms – 10000ms (5s – 10s)