diff --git a/main.tf b/main.tf
index 5c3ee20..64bddad 100644
--- a/main.tf
+++ b/main.tf
@@ -378,6 +378,9 @@ module "comet_elasticache" {
   elasticache_allow_from_sg = var.enable_ec2 ? module.comet_ec2[0].comet_ec2_sg_id : (
     var.enable_eks ? module.comet_eks[0].nodegroup_sg_id : (
   var.elasticache_allow_from_sg))
+  # EKS Auto Mode nodes attach the cluster primary SG (distinct from the managed node SG
+  # above), so grant them Redis access too when Auto Mode is enabled.
+  elasticache_auto_mode_allow_from_sg     = var.enable_eks && var.eks_enable_auto_mode ? module.comet_eks[0].cluster_primary_security_group_id : null
   elasticache_engine                      = var.elasticache_engine
   elasticache_engine_version              = var.elasticache_engine_version
   elasticache_instance_type               = var.elasticache_instance_type
@@ -408,11 +411,14 @@ module "comet_rds" {
   rds_allow_from_sg = var.enable_ec2 ? module.comet_ec2[0].comet_ec2_sg_id : (
     var.enable_eks ? module.comet_eks[0].nodegroup_sg_id : (
   var.rds_allow_from_sg))
-  rds_engine            = var.rds_engine
-  rds_engine_version    = var.rds_engine_version
-  rds_instance_type     = var.rds_instance_type
-  rds_instance_count    = var.rds_instance_count
-  rds_storage_encrypted = var.rds_storage_encrypted
+  # EKS Auto Mode nodes attach the cluster primary SG (distinct from the managed node SG
+  # above), so grant them MySQL access too when Auto Mode is enabled.
+  rds_auto_mode_allow_from_sg = var.enable_eks && var.eks_enable_auto_mode ? module.comet_eks[0].cluster_primary_security_group_id : null
+  rds_engine                  = var.rds_engine
+  rds_engine_version          = var.rds_engine_version
+  rds_instance_type           = var.rds_instance_type
+  rds_instance_count          = var.rds_instance_count
+  rds_storage_encrypted       = var.rds_storage_encrypted
 
   # Aurora Serverless v2 (optional)
   rds_serverless_v2_enabled                  = var.rds_serverless_v2_enabled
@@ -460,8 +466,13 @@ module "comet_rds_proxy" {
   vpc_id     = var.enable_vpc ? module.comet_vpc[0].vpc_id : var.comet_vpc_id
   subnet_ids = var.enable_vpc ? module.comet_vpc[0].private_subnets : var.comet_private_subnets
 
-  allowed_sg_ids = var.enable_eks ? [module.comet_eks[0].nodegroup_sg_id] : var.rds_proxy_allowed_sg_ids
-  allowed_cidrs  = var.rds_proxy_allowed_cidrs
+  # Managed node SG + (when Auto Mode is enabled) the cluster primary SG that Auto Mode
+  # nodes attach, so pods on either node type can reach the RDS proxy.
+  allowed_sg_ids = var.enable_eks ? concat(
+    [module.comet_eks[0].nodegroup_sg_id],
+    var.eks_enable_auto_mode ? [module.comet_eks[0].cluster_primary_security_group_id] : [],
+  ) : var.rds_proxy_allowed_sg_ids
+  allowed_cidrs = var.rds_proxy_allowed_cidrs
 
   mysql_cluster_id      = module.comet_rds[0].mysql_cluster_id
   mysql_sg_id           = module.comet_rds[0].mysql_sg_id
diff --git a/modules/comet_eks/outputs.tf b/modules/comet_eks/outputs.tf
index 6adef09..631c7e3 100644
--- a/modules/comet_eks/outputs.tf
+++ b/modules/comet_eks/outputs.tf
@@ -14,10 +14,15 @@ output "cluster_certificate_authority_data" {
 }
 
 output "nodegroup_sg_id" {
-  description = "ID of the node shared security group"
+  description = "ID of the node shared security group (managed node groups attach this)"
   value       = module.eks.node_security_group_id
 }
 
+output "cluster_primary_security_group_id" {
+  description = "EKS-managed cluster primary security group. EKS Auto Mode nodes attach this SG (managed node groups use nodegroup_sg_id instead) — reference it where Auto Mode nodes need network access (e.g. data-layer SG ingress)."
+  value       = module.eks.cluster_primary_security_group_id
+}
+
 output "cluster_autoscaler_irsa_role_arn" {
   description = "ARN of the Cluster Autoscaler IRSA role (serviceAccountName=kube-system/cluster-autoscaler). Wire this into the cluster-autoscaler Helm values as the service account annotation."
   value       = var.eks_enable_cluster_autoscaler ? module.cluster_autoscaler_irsa_role[0].iam_role_arn : null
diff --git a/modules/comet_elasticache/main.tf b/modules/comet_elasticache/main.tf
index 85b8bef..351bfc5 100644
--- a/modules/comet_elasticache/main.tf
+++ b/modules/comet_elasticache/main.tf
@@ -65,6 +65,20 @@ resource "aws_vpc_security_group_ingress_rule" "redis_port_inbound_rule" {
   ip_protocol                  = "tcp"
   referenced_security_group_id = var.elasticache_allow_from_sg
 }
+
+# EKS Auto Mode nodes attach the cluster primary SG (not the managed node SG that
+# elasticache_allow_from_sg references), so they need their own ingress rule to reach
+# Redis. Only created when the Auto Mode SG is passed in.
+resource "aws_vpc_security_group_ingress_rule" "redis_port_inbound_auto_mode" {
+  count = var.elasticache_auto_mode_allow_from_sg != null ? 1 : 0
+
+  security_group_id            = aws_security_group.redis_inbound_sg.id
+  from_port                    = local.redis_port
+  to_port                      = local.redis_port
+  ip_protocol                  = "tcp"
+  referenced_security_group_id = var.elasticache_auto_mode_allow_from_sg
+  description                  = "Redis from EKS Auto Mode nodes (cluster primary SG)"
+}
 # VPN ingress to Redis (DND-752) — gated by enable_vpn_redis_access. Allows
 # operators on the VPN to connect to Redis via kubectl port-forward through
 # the cluster's Redis SG.
diff --git a/modules/comet_elasticache/variables.tf b/modules/comet_elasticache/variables.tf
index d30e790..9aea48f 100644
--- a/modules/comet_elasticache/variables.tf
+++ b/modules/comet_elasticache/variables.tf
@@ -18,6 +18,12 @@ variable "elasticache_allow_from_sg" {
   type        = string
 }
 
+variable "elasticache_auto_mode_allow_from_sg" {
+  description = "Additional security group allowed to reach ElastiCache — the EKS Auto Mode cluster primary SG. Auto Mode nodes attach a different SG than managed node groups, so without this a pod on an Auto Mode node cannot reach Redis. Null (default) creates no extra rule."
+  type        = string
+  default     = null
+}
+
 variable "elasticache_engine" {
   description = "Engine type for Elasticache cluster"
   type        = string
diff --git a/modules/comet_rds/main.tf b/modules/comet_rds/main.tf
index d10a3b0..9f08d32 100644
--- a/modules/comet_rds/main.tf
+++ b/modules/comet_rds/main.tf
@@ -254,3 +254,17 @@ resource "aws_vpc_security_group_ingress_rule" "mysql_port_inbound_ec2" {
   ip_protocol                  = "tcp"
   referenced_security_group_id = var.rds_allow_from_sg
 }
+
+# EKS Auto Mode nodes attach the cluster primary SG (not the managed node SG that
+# rds_allow_from_sg references), so they need their own ingress rule to reach MySQL.
+# Only created when the Auto Mode SG is passed in.
+resource "aws_vpc_security_group_ingress_rule" "mysql_port_inbound_auto_mode" {
+  count = var.rds_auto_mode_allow_from_sg != null ? 1 : 0
+
+  security_group_id            = aws_security_group.mysql_sg.id
+  from_port                    = local.mysql_port
+  to_port                      = local.mysql_port
+  ip_protocol                  = "tcp"
+  referenced_security_group_id = var.rds_auto_mode_allow_from_sg
+  description                  = "MySQL from EKS Auto Mode nodes (cluster primary SG)"
+}
diff --git a/modules/comet_rds/variables.tf b/modules/comet_rds/variables.tf
index c1976d0..20e3d31 100644
--- a/modules/comet_rds/variables.tf
+++ b/modules/comet_rds/variables.tf
@@ -35,6 +35,12 @@ variable "rds_allow_from_sg" {
   type        = string
 }
 
+variable "rds_auto_mode_allow_from_sg" {
+  description = "Additional security group allowed to reach RDS — the EKS Auto Mode cluster primary SG. Auto Mode nodes attach a different SG than managed node groups, so without this a pod on an Auto Mode node cannot reach MySQL. Null (default) creates no extra rule."
+  type        = string
+  default     = null
+}
+
 variable "rds_engine" {
   description = "Engine type for RDS database"
   type        = string