Enabling/Disabling AWS Load Balancer Target Nodes for Maintenance

Question: Is there any way to temporarily disable/re-enable Network Load Balancer Target Group nodes for maintenance like we usually do with other load balancers?

Background: We have a distributed replicated LDAP service that serves our enterprise. It is based in multiple datacenters of various architectures. We have several representative LDAP nodes in AWS under a Network Load Balancer to provide service to our AWS-based applications. These LDAP nodes each hold a replicated copy of the entire directory, which consists of 1.8 million accounts plus attendant groups and other structures. The service is more akin to a database and loading the data can take a few hours, so the nodes aren't so amenable to auto-scaling processes. These nodes run RHEL7 and 389 Directory Server.

Attempted Solution: I've tried draining/re-registering each node for maintenance but it didn't work particularly well as the connections don’t seem to get killed reliably when drained and the whole drain/re-register operation takes a long time. I also don't want to have to rebuild my target group every time I do maintenance on the nodes

Thanks a lot