Hi @vagos1103gr,
I moved your post to a new thread as I don’t think your buffering problem directly related to what was discussed in that thread.
Did you use sudo nano /etc/apt/sources.list ?
How do you want to play a 140 Mbit file over a 100 Mbit LAN connection? Buffering only helps to buffer for peaks. Any file above 86Mbit average bandwidth will not be able to be played via Ethernet unless you get a USB Gigabit dongle.
Install iperf with sudo apt-get install iperf3 you then need to install it also on your NAS. You then would start it on the NAS with iperf3 -s and on the Vero4k with iperf3 -R -c <IP of the NAS>
No need to change that anymore, latest OSMC update ensures best settings on Vero4k