You replace the SSL certificate on Site Recovery Manager to keep the communication with this component trusted. You generate a custom certificate by using the CertGenVVS utility.
If you replace the certificates of all management components in each site, you must replace the certificates of all vCenter Server and NSX Manager instances before Site Recovery Manager to ensure a two way trust.
Prerequisites
Verify that a signed certificate, generated by the CertGenVVS utility (see https://kb.vmware.com/s/article/85527), is available for the Site Recovery Manager instance.