The MX HA pair in front of all the switches is down. There's no way a name change in dashboard would take down MX's and MS's (or any Meraki device).
What is 172.16.45.229? That is the default 0/0 route on your switches. Your AP's are still up and take that path to the internet. Whatever it is appears to have been connected to core switch 1 port 1 and the port is named IPVPN Primary. I assume something was done upstream on whatever that device is that broke your connectivity.
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