Is the Core also connected via WiFi? As noted in our requirements, we recommend that the Core be connected via Ethernet whenever possible. Can you give this a try and let us know if it helps?
As a temporary test, can you please try connecting the Core and Macbook via Ethernet to the router? Is there any change in behavior if they are connected this way?
Also, how often would you say you are seeing this issue occur? Once a day? More/less?