Question:

Why am I receiving a connectivitycheck.gstatic.com message when I connect to the Ui mixer's hotspot?

Answer:

Connectivitycheck.gstatic.com is one of many subdomains of gstatic.com. Gstatic.com is a web domain used by Google for accessing the Gstatic server: aserver where Google hosts its static content like CSS, Javascript code and images. It is used by Chrome and Android devices to check if a user has internet access to the network they are connected to, if not, the browser will load the captive portal login webpage, or else it will let the users access the internet. In short, the message received is only given when the wifi you are connecting to does not have internet service.  ​