Please read over all of this, then go back and start at the top of the list and try setting up the hub with each suggestion.

Let’s start off by clearing the wifi credentials on the hub.  You’ll need a toothpick or plastic pick.  You don’t want to use something metal to avoid static shock on the electronics.
http://support.clever.pet/how-do-i-clear-old-wifi-credentials-from-my-hub

One thing that I tripped up on when first trying to connect a hub was after the light blinks blue, you will need to put the dome back on, then proceed with the app.  For me, this seemed to mess up the whole process if I touched the center light 3 times and didn't put the dome back on.  It kind of half way connected.  So try that if you haven't already.
Additional information on that.
http://support.clever.pet/connecting-to-wifi/troubleshooting/what-if-i-need-to-set-up-the-hub-in-a-new-location-or-on-a-different-wifi-network

If you are on Android, Samsung phones can be problematic at times, the S6, S7 or later.  Even the Google Pixel phones can fail during setup.  So if you can try another brand if you haven't already, that would be good.
http://support.clever.pet/the-cleverpet-mobile-app/general-faq/is-my-phone-compatible-with-the-hub

Sometimes clearing the cache from the app can be more effective than uninstalling and reinstalling.   To do this, you go to the system settings in your phone, then > Apps > CleverPet > Storage > Clear Cache, or even Clear Data, if you are confident you know your account credentials. Note: These are the instructions for Android.  iOS does not have this option and uninstalling and reinstalling will be your best option. 

Keep in mind, 5ghz and security settings other than WPA2 do not work well with our hub.  So I would suggest, 2.4ghz and WPA2 for your signal and security settings on your router.
http://support.clever.pet/connecting-to-wifi/general-faq/is-my-wifi-router-compatible-with-the-hub

Last thing, and this goes back to me trying to setup the hub without reading the instructions, but I used my phone wifi connection system to connect to the CleverPet hub before opening the app and following the steps to connect.  This won't work, because the app expects you to be connected to your home wifi during the initial part of the setup, then it will look for the CleverPet hotspot and connect to that during the setup process.
http://support.clever.pet/connecting-to-wifi/troubleshooting/im-running-into-an-error-when-trying-to-connect-to-the-photon-network-android

Additional information about Wifi compatibility
http://support.clever.pet/connecting-to-wifi/troubleshooting/wifi-setup-troubleshooting-the-complete-guide