Interesting. I managed to get to the customer, large residential install, and discovered the issue being access point interference which only impacted services like WhatsApp, Favetime and VoIP    Access points are all Meraki-Go, and noticed some 2.4 channels were weaker than others and the IPhone would identify as poor connection, dropping WiFi and then re-establish.  auto-channel seemed to be conflicting    Switched off the access points, bringing them back one at a time and resulting in the removal of one access point.  WhatsApp, FaceTime etc now working fine!  ... View more

What is your setup?   for example, meshed networks have a bandwidth cost penalty per hop.     ... View more

Thanks @alemabrahao - I've posted it there  ... View more