When DFS is not replicating anymore and you see event ID 2104 with error 9214 there is a simple solution to do which i found on this website: http://www.asptricks.net/2017/01/replication-service-failed-to-recover.html
Basicly it’s disabling the replication group nodes and running a .bat file.
1. Disable group replication (DFS Management -> Replication -> Replication group -> Connections -> disable the group members.
2. Create a .bat file with the following content:
REM Removes the broken DFSR configuration database from the system
net stop dfsr
icacls "%DFSR_DB_DRIVE%\System Volume Information" /grant "Domain Admins":F
cd "%DFSR_DB_DRIVE%\System Volume Information"
move DFSR %DFSR_DB_DRIVE%\DFSR_backup
icacls "%DFSR_DB_DRIVE%\System Volume Information" /remove:g "Domain Admins"
net start dfsr
dfsrdiag PollAD /Member:%userdomain%\%computername%