Asus AC66u b1 network sharing

Hi,
I have some PCs, couple laptops and a Raspberry PI3.
Have a proble4m sharing folder to all computers.
This has really been a struggle for years. Read and tried everything.

I get a feeling that is matters which connection type machines use.
Some are wired, some might be on 2g wifi and some on 5g wifi.

Does is matter or should not interfere in any way with sharing?
Any settings that might be wrong in router?

Thanks!

BR,Peter