I had the same issue,had massive memory leaks and after a day or so the nuc just froze up.i reinstalled 20.04 5 times and reinstalled Dappnode each time but with the same outcome.
Have been running Validators through 20.04 terminal the last week with no issue.
Yeah, I´ve had to do a few power shutdowns when it freezes. But this is the third time I´ve reinstalled ubuntu and dappnode and I never power shutdown before it freezes.
Last time I reinstalled I tried only running one package (synching geth) but it shuts down after maybe 12 hours of synching. Then I get the same error as in this thread: Error code and Node shut down
I have now uninstalled dappnode and trying to sync geth from terminal.