Since I have solved my wifi instability problems, as described here:
I can now play 24 bit flac files on my hifiberry dac+pro setup. It seems that the dac+pro causes specific interference with the built in wifi which greatly reduces the bandwidth and stability. This interference is only evident at specific frequencies corresponding to specific wifi channels. By fixing my wifi router to broadcast on channel 4, the interference is no longer an issue and the setup now works for 24bit files. I don’t know if channel 4 is a general recommendation, but it works for me.