If your bandwitch allows it, this will enable stutter free streaming of 4K remuxes over CIFS/VPN/WAN.
sudo wget 'https://gist.github.com/hekmon/78b30ae8cb76b076d01bddaf79b2c693/raw/d063a1bee463745ce2b8ded41475b5d9c179c7b4/sysctl.conf' -O '/etc/sysctl.d/90-CIFS_over_WAN.conf'
sudo sysctl -p