Exchange 2016 Database Replication Speed

I am working in Exchange 2016 mutli-site DAG with 12 nodes.

I am observing database copy seeding speed to slow, although i have replication link of 10G but seeding speed won't cross 1.2Gbps.please guide how can i improve database seeding speed.

I even tried -nothrottle switch with update-mailboxdatabasecopy.