Go to My Grid / Device Manager.

Your device will be connected to one of the four BOINC profiles:
default, home, school, work ... most likely default unless you have set some different project options for different devices.

Go to the appropriate profile.

Close to the bottom, you see this:

Workunit Cache Settings
Connect to network about every [0.1] days

The default queue is only 2.4 hours, which is not very much. You can ask for a few days in there, but don't get greedy. 7.0 is not advised, because the BOINC scheduler does strange things like cleaning out the queue before you get more work.

I have had good luck by setting this parameter between 1.0 and 3.0 days. You want the queue to remain relatively full, to last through maintenance periods or other nonconnectivity. Whenever you send in a few workunits, you should get a few new ones at the bottom of the queue to work on, sometimes after a short delay to spread the server workload.

After setting the parameter, you can either go to the project tab to force an update to your worldcommunitygrid project in BOINC, or you can wait for the next upload to do it.

Thx for answers - Will look into it.
Greetings Belmarduk