Samsung Note8 wifi issue (connectivity.samsung.com.cn) I captured this screen when using WiFi with web authentication
First it goes to the connectivity.Samsung.com.cn

Then to the  wifi login screen
This is weird, does my wifi info exposing?

*I bought this phone in Hong Kong.
The domain samsung.com.cn is just an alias of samsung.com/cn. It is the Samsung domain for China. The fact that you bought the phone when you were in Hong Kong validates it.

connectivity.samsung.com.cn is a subdomain that your phone checks when you're connected to WiFi or mobile data to know if it is able to "talk" to the mothership (in this case Samsung servers). Type the URL in your browser and you will get Ok if the link is established.

So when you are connected, your phone establishes a link with Samsung servers (just as it does with Google if you have Play services installed). Your phone has not been exposed to hackers but is calling home possibly to check if there are updates from Samsung for your phone.