Changing Horizons in a running EKS instance

Hello, I am currently in charge of maintaining a running Mongo Community Operator deployment that was made by a previous company.
There is now a need to connect to said Mongo externally, using a VPN to connect to the EKS and then somehow connect to Mongo via ReplicaSet. I was able to expose the mongo instances by using LoadBalancers, but the problem now is that once the connection is stablished and the ReplicaSetMonitor takes over the internal addresses of the mongo replicas are not discoverable from outside the EKS.

Step by step, the client connects via VPN to the EKS, then it connects to the mongo deployment via connection string, using the LoadBalancer’s public IP as connection seeds in the connection string. This connection is successful; but, when the ReplicaSetMonitor tries to reconnect to the different replicas using the internal configuration it fails since the client can’t resolve the names that the ReplicaSetMonitor tries to use for the new connection.
From what I understand, to resolve this I should modify the mongo config horizons, to add the LoadBalancer’s public IPs in those fields. I’d like to know if this is indeed a viable solution and if so how to change those configs (if possible without having to redeploy the mongo instance).

If none of the previous solutions are valid I was thinking of deploying a new Mongo Operator deployment in a different namespace and tweak it as necessary without risking anything in the productive one. For this, I saw that a cert manager is also deployed, I was wondering if each deployment’s cert manager could interfere with each other despite being in different namespaces.

Mind you this is all conclusions from my limited understanding of this process as read in multiple online forums, so if anything is out of field do refer me to some more documentation which could prove useful.

Thanks in advance!