Samsung smart TV

I have a strange problem and apologies if I struggle to explain it

On my home network, I have three QNAP NAS devices

Last week when I went to the smart hub in my Samsung TV all three of them showed up as connected devices

This week NONE of them do

I’m not sure what’s changed (if anything) so I am at a loss to try and debug

Any suggestions on what to look for, or what settings need to be enabled to make them visible will be gratefully received