How can I use cloudflare tunnel for MongoDB replicaset?

I am trying to setup a mongo replicaset between 2 servers which has no private connectivity with each other via Cloudflare tunnels. I am assuming since mongodb replication involves primary communicating with secondary continuously I created 2 tunnels for both the primary and the secondary.

primary - routed on the dns linux1.domain.com:27017
Private IP - 172.16.0.4
Public IP - 20.190.2.35

secondary - routed on the dns linux2.domain.com:27017
Private IP - 172.17.0.4
Public IP - 10.210.2.44

however upon adding the secondary (linux2.domain.com:27017) on the replicaset, the node can’t be reached by the primary.