DFSR replication of sysvol is much more reliable, and NTFRS is being deprecated after Windows Server 2016.
This is how to migrate to DFSR. The information here is gleamed from :
https://blogs.technet.microsoft.com/filecab/2014/06/25/streamlined-migration-of-frs-to-dfsr-sysvol/
and the long version:
https://technet.microsoft.com/en-us/library/dd640019%28v=WS.10%29.aspx?f=255&MSPPError=-2147217396
Check forest functional level using domain.msc and raise if below 2008.
Force a replication with:
Repadmin /syncall /force /APed
this is optional, but will speed things up, and you can use this replication to check for errors.
Check event log for errors, especially the File Replication Service logs.
Repadmin /replsummary
Check that replication is working.
Dcdiag /e /test:sysvolcheck /test:advertising
Fix any errors.
Next the migration.
dfsrmig /setglobalstate 1
Run
dfsrmig /getmigrationstate
Do not proceed further until it tells you that “All domain controllers have migrated successfully to the Global state.”
dfsrmig /setglobalstate 2
Again check it with
dfsrmig /getmigrationstate
And make sure all DCs have migrated.
Finally
dfsrmig /setglobalstate 3
And it is finished when
dfsrmig /getglobalstate
tells you that all DCs have migrated successfully.
You can apparently go straight to state 3, but it doesn’t take long to go the full route, so better taking a little time.