Working with control stations can be tricky sometimes. One of the well-known issues is that while control station is connected, the internet connection will fail. There is an entire article on this matter on our support portal: https://support.smartptt.com/hc/en-us/articles/200250597-No-Internet-connection-when-Control-Station-is-connected
However, we have seen another point related to that. Do you know about multiple Default Gateway configuration?
In this configuration window, you can see another gateway, added with its own metric, set to automatic. Pay attention, this metric can stand in the way. Get it sorted out, set it to the same metric as in the main configuration, and the internet should return.