CDCR - shards not in sync

[Jay Potharaju]

Hi,
I have a collection with 8 shards. 6 out of the shards are in sync but the
other 2 are lagging behind by more than 10 plus hours. The tlog is only 0.5
GB in size. I have tried stopping and starting CDCR number of times but it
has not helped.
>From what i have noticed there is always a shard that is slower than others.

Solr version: 7.7.0
CDCR config

  <lst name="replicator">
            <str name="threadPoolSize">2</str>
            <str name="schedule">10</str>
            <str name="batchSize">4500</str>
          </lst>

          <lst name="updateLogSynchronizer">
            <str name="schedule">60000</str>
          </lst>


Thanks
Jay