diff --git a/argocd/applications/custom/edgenode-observability.tpl b/argocd/applications/custom/edgenode-observability.tpl
index c754ad763..d72757d4b 100644
--- a/argocd/applications/custom/edgenode-observability.tpl
+++ b/argocd/applications/custom/edgenode-observability.tpl
@@ -555,6 +555,12 @@ mimir-distributed:
     {{- end }}
     ingress:
       enabled: false
+    # Buffer settings to handle large headers/cookies
+    nginx:
+      config:
+        serverSnippet: |
+          client_header_buffer_size 64k;
+          large_client_header_buffers 64 128k;
     {{- if and .edgeNode .edgeNode.mimir .edgeNode.mimir.gateway }}
     {{- if .edgeNode.mimir.gateway.replicas }}
     replicas: {{ .edgeNode.mimir.gateway.replicas }}
diff --git a/argocd/applications/custom/orchestrator-observability.tpl b/argocd/applications/custom/orchestrator-observability.tpl
index ca0780bd8..9458cf3bd 100644
--- a/argocd/applications/custom/orchestrator-observability.tpl
+++ b/argocd/applications/custom/orchestrator-observability.tpl
@@ -246,6 +246,12 @@ mimir-distributed:
   gateway:
     ingress:
       enabled: false
+    # Buffer settings to handle large headers/cookies
+    nginx:
+      config:
+        serverSnippet: |
+          client_header_buffer_size 64k;
+          large_client_header_buffers 64 128k;
     {{- if and .Values.argo.o11y .Values.argo.o11y.orchestrator .Values.argo.o11y.orchestrator.mimir }}
     {{- with .Values.argo.o11y.orchestrator.mimir }}
     {{- if .replicas }}