PCM is sent as file bytes when accessed from NAS, so definitely not 32 bits per sample. And 4K video streaming works fine over exactly the same wireless repeater as the one used for audio duties.
Sure... So as I said earlier the problem is somewhere else, maybe NAS or something?
I just tested with my laptop connected to WiFi, from my Linux server running Samba, SMB mount to my laptop and NAA connection to Mac Mini where exaSound e28 DAC is connected. I can play 5.0 channel DSD256 file from the network share through HQPlayer to 8 channel output at DSD256 to the NAA/DAC. So the data is going over the WiFi twice, plus three extra channels being sent to the NAA. And still it works...