Typically, the 700003 error code indicates that the computer’s machine account cannot be found in Azure Active Directory.
Recentley I encountered a situation that had dozens of systems showing the error message. It was difficult to explain how that many system accounts could have been removed from Azure AD.
Eventually I traced the problem to some work another team was doing. They were reorganizing on-prem computer accounts into new organisational units. The Azure AD Connect configuration pointed at specific OUs and nobody had thought to add the new ones.
As the systems were moved to their new OUs they were marked for deletion by Azure AD Connect. The fix was to add the new organization units to ADC and force a synch.