Thanks to your support team for solving my problem.
I changed that setting to 6:00 but the process still hangs up in the same place after around 70sec ..during the same process “sending of backup to dropbox”, this time at 52%. Two files appear in dropbox before the process fails.. They have my website name-full-the date and time-1.zip and the same name -10.zip
Having stopped doing anything at around 70 sec the plugin stays live and counting for over 600sec but nothing new happens.
the max_execution_time is exceeded at 120 but since the process stops at 7 that doesn’t seem relevant. I guess I need a different remote backup solution. This one only works saving the backup to the local server. It is not clear why so much time is required for such a small backup, 14MB on the local server.