Then, if I understand, the Mate3 responds to a ping from the software every 20 seconds, and sends a data package to the server, right? My question is why 20 seconds? I would rather see what is going on at 5 or 10 second intervals.

I can't be certain, since I don't work for Outback and haven't reverse engineered their protocol, but I don't expect that the pings do data collection. They are normally the shortest possible messages to verify that a device is online. Separate messages most likely respond to pings periodically to dump the stored data from the MATE3. Doing otherwise might jam the communication channel with everyone doing it at once and no flow control and as it is I've seen the data collection get behind a day or so probably taking care of so many systems after an outage & trying to catch up.