diff --git a/kona/docker/fpvm-prestates/justfile b/kona/docker/fpvm-prestates/justfile
index 0f5849f995f1e..50f096ece377a 100644
--- a/kona/docker/fpvm-prestates/justfile
+++ b/kona/docker/fpvm-prestates/justfile
@@ -41,8 +41,18 @@ build-client-prestate-cannon-artifacts \
   mkdir -p $OUTPUT_DIR
 
   echo "Building kona-client (variant: {{kona_client_variant}}) prestate artifacts for the cannon target. 🔫 Cannon Tag: {{cannon_tag}}"
+
+  # Build the --allow flag conditionally (requires Docker Buildx v0.15.0+)
+  ALLOW_FLAG=""
+  BUILDX_VERSION=$(docker buildx version 2>/dev/null | grep -oE '[0-9]+\.[0-9]+\.[0-9]+' | head -1 || echo "0.0.0")
+  MAJOR=$(echo "$BUILDX_VERSION" | cut -d. -f1)
+  MINOR=$(echo "$BUILDX_VERSION" | cut -d. -f2)
+  if [[ "$MAJOR" -gt 0 ]] || [[ "$MAJOR" -eq 0 && "$MINOR" -ge 15 ]]; then
+    ALLOW_FLAG="--allow fs=${CUSTOM_CONFIGS_CONTEXT}"
+  fi
+
   docker buildx bake \
     --set "*.output=$OUTPUT_DIR" \
     -f docker/docker-bake.hcl \
-    --allow fs=${CUSTOM_CONFIGS_CONTEXT} \
+    $ALLOW_FLAG \
     kona-cannon-prestate
diff --git a/op-devstack/sysgo/l1_nodes.go b/op-devstack/sysgo/l1_nodes.go
index d6dc3baa002ff..1f8d879434f21 100644
--- a/op-devstack/sysgo/l1_nodes.go
+++ b/op-devstack/sysgo/l1_nodes.go
@@ -131,11 +131,8 @@ func WithL1NodesInProcess(l1ELID stack.L1ELNodeID, l1CLID stack.L1CLNodeID) stac
 		})
 
 		l1ELNode := &L1Geth{
-			id: l1ELID,
-			// Use WS for user RPC so op-node components (and op-supernode virtual nodes)
-			// can subscribe to L1 head updates. Using HTTP here causes HeadL1 to remain zero,
-			// which can stall components like the batcher that wait for initialized sync status.
-			userRPC:  firstNonEmpty(l1Geth.Node.WSEndpoint(), l1Geth.Node.HTTPEndpoint()),
+			id:       l1ELID,
+			userRPC:  l1Geth.Node.HTTPEndpoint(),
 			authRPC:  l1Geth.Node.HTTPAuthEndpoint(),
 			l1Geth:   l1Geth,
 			blobPath: blobPath,
@@ -152,15 +149,6 @@ func WithL1NodesInProcess(l1ELID stack.L1ELNodeID, l1CLID stack.L1CLNodeID) stac
 	})
 }
 
-func firstNonEmpty(values ...string) string {
-	for _, v := range values {
-		if v != "" {
-			return v
-		}
-	}
-	return ""
-}
-
 // WithExtL1Nodes initializes L1 EL and CL nodes that connect to external RPC endpoints
 func WithExtL1Nodes(l1ELID stack.L1ELNodeID, l1CLID stack.L1CLNodeID, elRPCEndpoint string, clRPCEndpoint string) stack.Option[*Orchestrator] {
 	return stack.AfterDeploy(func(orch *Orchestrator) {