I actually ran into something similar about 2 months ago. Random reboots due to "low memory". I literally hadn't changed anything in the program for months, but all of a sudden I started seeing reboots, typically preceded by the NIC flapping.
I tried cleaning up, updating, etc but had no luck resolving it. I filed a ticket with Loxone and they suggested the SD card was likely failing, even if diagnostics showed everything was ok.
I had planned on upgrading my MS, so I did that instead of trying a new SD card. Once migrated to the new MS everything worked fine, suggesting either the SD card or the old MS itself was failing.