I did apply the MSFT Windows Server 20H2 - Domain Controller Baseline to my test enviromnent. All clients are fully functional. I added a new Domain Controller to the environment and the SYSVOL Replication won´t start.
Access to \\mydom.tld\sysvol from this new DC is fully functional, nltest /sc_query succesfull. Network Security LDAP requirements for clients is set to negotiate. DomainController is set to None
It happened in 2 ADs. Both are older ones, running since 2003/2008 and are migrated.
I installed a clean new AD on Server 2019, DFL/FFL 2016, added a secound DC. Applied MSFT Windows Server 20H2 - Domain Controller as an additional GPO, move it up to be the winning one on place 1. Created testfiles in Sysvol to check DFS-R Replication on both DCs in Filesystem. All tests successful, even after applying all Updates up to 01/2021. Rebootet always twice after doing checks.
The weird thing:
The GPO broke DFS-R in one of the ADs, we removed it, DFS-R was functional again, then we re-applied the GPO and now DFS-R is still running ... clueless ...