Okay - I'll try a factory reset of the SH2 and see if that helps. Can I check - I've noticed the channels that the hub uses for 2.4 and 5 GHz are quite full (according to the WiFi analyser app I used) - could changing the channels to something different do anything to help, or is that likely completely irrespective of the disconnects?
The wifi is completely irrelevant to the disconnects.