Intermittance power outage in control panel and kitchen

Hi. We are new to this. We have 1993 Excella. We are experencing power outages to the control panel, kitchen lights and refrigerator. It lasts anywhere from 5 minutes to several hours, and then everything comes back on. It happens when plugged in or on battery power. Anyone have any ideas? Usually happens after we have been parked for awhile. Last two time it was the morning we were leaving after a 2 day trip. Checked all of the fuses, but it shouldn't be a fuse because the power comes back on.

Thanks for any help on this.