This thesis aims to improve the MQTT communication between simulated Renewable Energy Communities (RECs) and an Energy Management System (EMS) by introducing load balancing and firewall protection between them. For the load-balancing side, the two-level load-balancing architecture is introduced: first, a standalone HAProxy on the REC side, and second, an HAProxy ingress load balancer with MetalLB on the central side. Both operate at the TCP layer and forward traffic over TLS. For the security side, firewall rules are configured to restrict incoming connections so that external hosts cannot access MQTT or management ports, helping to prevent potential attacks. The results show a scalable , secure routing of REC traffic through the two-layers load-balancer , which evenly balances and distributes the traffic between broker replicas and finally to the central brokers.