Pause replication, make the networks changes, then make the changes in via DM, then use the system connectivity test option from one of the RPA's via boxmgmt and if everything is OK resume replication.
I have cluster1 and cluster2, they connected normally, and remote copy CG is configured, if I use deploy manager to change WAN IP of cluster2, is the operation fully online? will the CG be impacted? and is there anything need to do to CLUSTER1 after the cluster Modification wizard of CLUSTER2 done? 
how to modify WAN IP address of one cluster when it is connected with others