Two problems:
1. Most often, even though my iphone 7 wifi settings shows I am connected to the Canon 6D (or 6D Mark II), qDslrDashbord's (V3.5.9) search is unable to connect.

2. Periodically I can get my iphone connected to qDslrDashboard. The "main screen" shows the horizontal bar and Connection info. I click on "Canon" but I don't get the screen that shows the sidebars so I am unable to launch LRTimelapse. Moments later I will get "Failed to connect with wireless. Try to disable mobile data and try again." I turned off cellular data but this did not help.

As long as you are not connected to your device, you won't get to the next screen.
I know of some users that are using a C6dMk2 with qDDB but I have no idea why it's not working for you.
Maybe Zoltan, the Developer of qDDB can tell more.