Yeah, you can switch the Drayteks to "Dialo out only" and "always on". This is the setup that always worked for us.
On the problematic sites I switched to dial in AND out, so it's initiated, when someone starts working at the site. But that does not really help. After 7,5 hours the pfsense initiates the reconnect and the Draytek shows, that its still connected.
The workaround at the time is to put up the phase 2 lifetime to 12 hours. So the problem occurs, when nobody is working.