Active Directory health reports shows errors

Hi,

Few weeks before we migrated our 3 DC's from 2008 R2 to 2016 currently both Forest & Domain functional lever is Windows Server 2008R2, everything seems to be fine but when generated AD Active Health report shows the following error message in all 3 DC's

1. Sysvol mode is not DFS-R

2. Advertising failed, consider running: dcdiag.exe /test:Advertising

3. DNS failed, consider running: dcdiag.exe /test:DNS

4. VerifyEnterpriseReferences failed, consider running: dcdiag.exe /test:verifyEnterpriseReference.

When executing the dcdiag receive with the following result, kindly advise further!

C:\Windows\system32>dcdiag.exe

Directory Server Diagnosis

Performing initial setup:
   Trying to find home server...
   Home Server = DC1
   * Identified AD Forest.
   Done gathering initial info.

Doing initial required tests

   Testing server: Default-First-Site-Name\DC1
      Starting test: Connectivity
         ......................... DC1 passed test Connectivity

Doing primary tests

   Testing server: Default-First-Site-Name\DC1
      Starting test: Advertising
         ......................... DC1 passed test Advertising
      Starting test: FrsEvent
         There are warning or error events within the last 24 hours after the SYSVOL has been shared.  Failing SYSVOL
         replication problems may cause Group Policy problems.
         ......................... DC1 passed test FrsEvent
      Starting test: DFSREvent
         ......................... DC1 passed test DFSREvent
      Starting test: SysVolCheck
         ......................... DC1 passed test SysVolCheck
      Starting test: KccEvent
         ......................... DC1 passed test KccEvent
      Starting test: KnowsOfRoleHolders
         ......................... DC1 passed test KnowsOfRoleHolders
      Starting test: MachineAccount
         ......................... DC1 passed test MachineAccount
      Starting test: NCSecDesc
         ......................... DC1 passed test NCSecDesc
      Starting test: NetLogons
         ......................... DC1 passed test NetLogons
      Starting test: ObjectsReplicated
         ......................... DC1 passed test ObjectsReplicated
      Starting test: Replications
         ......................... DC1 passed test Replications
      Starting test: RidManager
         ......................... DC1 passed test RidManager
      Starting test: Services
         ......................... DC1 passed test Services
      Starting test: SystemLog
         An error event occurred.  EventID: 0x00002720
            Time Generated: 07/06/2020   14:29:48
            Event String:
            The application-specific permission settings do not grant Local Activation permission for the COM Server application with CLSID
         An error event occurred.  EventID: 0x00002720
            Time Generated: 07/06/2020   14:30:31
            Event String:
            The application-specific permission settings do not grant Local Activation permission for the COM Server application with CLSID
         An error event occurred.  EventID: 0x00002720
            Time Generated: 07/06/2020   14:31:18
            Event String:
            The application-specific permission settings do not grant Local Activation permission for the COM Server application with CLSID
         ......................... DC1 failed test SystemLog
      Starting test: VerifyReferences
         ......................... DC1 passed test VerifyReferences


   Running partition tests on : DomainDnsZones
      Starting test: CheckSDRefDom
         ......................... DomainDnsZones passed test CheckSDRefDom
      Starting test: CrossRefValidation
         ......................... DomainDnsZones passed test CrossRefValidation

   Running partition tests on : ForestDnsZones
      Starting test: CheckSDRefDom
         ......................... ForestDnsZones passed test CheckSDRefDom
      Starting test: CrossRefValidation
         ......................... ForestDnsZones passed test CrossRefValidation

   Running partition tests on : Schema
      Starting test: CheckSDRefDom
         ......................... Schema passed test CheckSDRefDom
      Starting test: CrossRefValidation
         ......................... Schema passed test CrossRefValidation

   Running partition tests on : Configuration
      Starting test: CheckSDRefDom
         ......................... Configuration passed test CheckSDRefDom
      Starting test: CrossRefValidation
         ......................... Configuration passed test CrossRefValidation

   Running partition tests on : ***********
      Starting test: CheckSDRefDom
         ......................... *********** passed test CheckSDRefDom
      Starting test: CrossRefValidation
         ......................... *********** passed test CrossRefValidation

   Running enterprise tests on : ***********.com
      Starting test: LocatorCheck
         ......................... ***********.com passed test LocatorCheck
      Starting test: Intersite
         ......................... ***********.com passed test Intersite

C:\Windows\system32>

Thanks in advance