4k over lan possible?

I have my blu rays ripped as mkv etc. Sizes are around 10 to 60 gb.

It starts off well when playing over LAN but then the buffering and freezing begins.

Is it possible or has anyone got 4k over LAN working?

They work fine when transfered to a hdd and plugged into the tv directly and using the lg internal app to play them.

I tired advancedsettings but no joy. If i try the on-line streams they buffer a lot less and sometimes not at all.

Dont understand how strwaming the same file from the Internet works better than from my pc on the land without using the same lan and the Internet at 38mbs