CDCR is deprecated
This feature (in its current form) is deprecated and will be removed in 9.0.
Anyone currently using CDCR should consider migrating away from it.
There are several open issues which make CDCR complex to maintain and generally unstable.
The simplest alternative to CDCR is to manually maintain two Solr implementations in separate data centers and manage them as completely separate installations.
While this may require more initial setup, it will be more stable in the long run.
There are other alternatives, and the Solr community is working to identify the best recommended replacement in time for 9.0.