JUST ABOUT AS BAD A RING DOORBELL WIFI PRODUCTS... you will need to disable EVERYTHING on your router (VPN on router/phone, any MAC address restrictions on WiFi network, router's firewall, etc) in order to get the sync module to connect to the Blink servers (during initial set-up). Then, it will eventually just start disconnecting on it's own, and you will need to unplug-it/plug-in every other day or so to get it to connect again.
BUT, if you try and delete the sync module and start over, it will NEVER connect to the Blink servers ever again, it will just come back with "failure to connect, check your password", even though I never changed any of my passwords since the last time I got it connected (and I can see the connection sending/receiving packets on my router).
Apparently these are "known" firmware issues that are NEVER fixed. I would NOT recommend the Blink or Ring WiFi products unless you love tearing your hair out with the frustration of getting these things connected, and staying connected to your home network. I how have several hundred dollars of products that are TOTALLY USELESS (and their support sucks!).