diff --git a/.github/pull_request_template.md b/.github/pull_request_template.md
index 571053fb..aaa704fd 100644
--- a/.github/pull_request_template.md
+++ b/.github/pull_request_template.md
@@ -11,4 +11,4 @@
 Fixes #<issue number>
 
 **Checklist**
-- [ ] `CHANGELOG.md` updated - the order of entries should be `[CHANGE]`, `[FEATURE]`, `[ENHANCEMENT]`, `[BUGFIX]`
\ No newline at end of file
+- [ ] `CHANGELOG.md` updated - the order of entries should be `[CHANGE]`, `[FEATURE]`, `[ENHANCEMENT]`, `[BUGFIX]`, `[DEPENDENCY]`
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 343cc599..08034e21 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## master / unreleased
 
+* [ENHANCEMENT] Add `nginx.config.upstream_protocol` field to configure the upstream protocol in the nginx configuration #506
+* [BUGFIX] fix: upstream_protocol reference in auth_orgs #509
+* [DEPENDENCY] Update quay.io/cortexproject/cortex Docker tag to v1.18.1 #510
+
 ## 2.4.0 / 2024-07-18
 
 * [CHANGE] Removed the default `livenessProbe` for store-gateway and compactor. You can still use a `livenessProbe` but we advise against it #502
diff --git a/Chart.yaml b/Chart.yaml
index 2bb55955..b4e6c29e 100755
--- a/Chart.yaml
+++ b/Chart.yaml
@@ -1,6 +1,6 @@
 apiVersion: v2
 version: 2.4.0
-appVersion: v1.17.1
+appVersion: v1.18.1
 description: 'Horizontally scalable, highly available, multi-tenant, long term Prometheus.'
 home: https://cortexmetrics.io/
 icon: https://avatars2.githubusercontent.com/u/43045022?s=200&v=4
@@ -9,7 +9,7 @@ maintainers:
   - email: thayward@infoblox.com
     name: Tom Hayward
     url: https://github.com/kd7lxl
-  - email: Niclas.Schad@mail.schwarz
+  - email: niclas.schad@stackit.cloud
     name: Niclas Schad
     url: https://github.com/nschad
 name: cortex
diff --git a/MAINTAINERS.md b/MAINTAINERS.md
index f5ee26c2..b0a65fd5 100644
--- a/MAINTAINERS.md
+++ b/MAINTAINERS.md
@@ -1,2 +1,2 @@
-- Niclas Schad, STACKIT <Niclas.Schad@mail.schwarz> ([@nschad](https://github.com/nschad))
+- Niclas Schad, STACKIT <niclas.schad@stackit.cloud> ([@nschad](https://github.com/nschad))
 - Tom Hayward, Infoblox <thayward@infoblox.com> ([@kd7lxl](https://github.com/kd7lxl))
diff --git a/README.md b/README.md
index c7d420cb..4c2295cb 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 # cortex
 
-![Version: 2.4.0](https://img.shields.io/badge/Version-2.4.0-informational?style=flat-square) ![AppVersion: v1.17.1](https://img.shields.io/badge/AppVersion-v1.17.1-informational?style=flat-square)
+![Version: 2.4.0](https://img.shields.io/badge/Version-2.4.0-informational?style=flat-square) ![AppVersion: v1.18.1](https://img.shields.io/badge/AppVersion-v1.18.1-informational?style=flat-square)
 
 Horizontally scalable, highly available, multi-tenant, long term Prometheus.
 
@@ -13,7 +13,7 @@ Horizontally scalable, highly available, multi-tenant, long term Prometheus.
 | Name | Email | Url |
 | ---- | ------ | --- |
 | Tom Hayward | <thayward@infoblox.com> | <https://github.com/kd7lxl> |
-| Niclas Schad | <Niclas.Schad@mail.schwarz> | <https://github.com/nschad> |
+| Niclas Schad | <niclas.schad@stackit.cloud> | <https://github.com/nschad> |
 
 ## Documentation
 
@@ -439,6 +439,7 @@ Kubernetes: `^1.19.0-0`
 | nginx.&ZeroWidthSpace;config.&ZeroWidthSpace;mainSnippet | string | `""` | arbitrary snippet to inject in the top section of the nginx config |
 | nginx.&ZeroWidthSpace;config.&ZeroWidthSpace;serverSnippet | string | `""` | arbitrary snippet to inject in the server { } section of the nginx config |
 | nginx.&ZeroWidthSpace;config.&ZeroWidthSpace;setHeaders | object | `{}` |  |
+| nginx.&ZeroWidthSpace;config.&ZeroWidthSpace;upstream_protocol | string | `"http"` | protocol for the communication with the upstream |
 | nginx.&ZeroWidthSpace;config.&ZeroWidthSpace;verboseLogging | bool | `true` | Enables all access logs from nginx, otherwise ignores 2XX and 3XX status codes |
 | nginx.&ZeroWidthSpace;containerSecurityContext.&ZeroWidthSpace;enabled | bool | `true` |  |
 | nginx.&ZeroWidthSpace;containerSecurityContext.&ZeroWidthSpace;readOnlyRootFilesystem | bool | `false` |  |
diff --git a/templates/nginx/nginx-config.yaml b/templates/nginx/nginx-config.yaml
index 7db8b83a..7945a0ef 100644
--- a/templates/nginx/nginx-config.yaml
+++ b/templates/nginx/nginx-config.yaml
@@ -81,20 +81,20 @@ data:
 
         # Distributor Config
         location = /ring {
-          proxy_pass      http://{{ template "cortex.fullname" . }}-distributor.{{ $rootDomain }}$request_uri;
+          proxy_pass      {{ .Values.nginx.config.upstream_protocol }}://{{ template "cortex.fullname" . }}-distributor.{{ $rootDomain }}$request_uri;
         }
 
         location = /all_user_stats {
-          proxy_pass      http://{{ template "cortex.fullname" . }}-distributor.{{ $rootDomain }}$request_uri;
+          proxy_pass      {{ .Values.nginx.config.upstream_protocol }}://{{ template "cortex.fullname" . }}-distributor.{{ $rootDomain }}$request_uri;
         }
 
         location = /api/prom/push {
-          proxy_pass      http://{{ template "cortex.fullname" . }}-distributor.{{ $rootDomain }}$request_uri;
+          proxy_pass      {{ .Values.nginx.config.upstream_protocol }}://{{ template "cortex.fullname" . }}-distributor.{{ $rootDomain }}$request_uri;
         }
 
         ## New Remote write API. Ref: https://cortexmetrics.io/docs/api/#remote-write
         location = /api/v1/push {
-          proxy_pass      http://{{ template "cortex.fullname" . }}-distributor.{{ $rootDomain }}$request_uri;
+          proxy_pass      {{ .Values.nginx.config.upstream_protocol }}://{{ template "cortex.fullname" . }}-distributor.{{ $rootDomain }}$request_uri;
         }
 
         {{- end }}
@@ -103,19 +103,19 @@ data:
 
         # Alertmanager Config
         location ~ /api/prom/alertmanager/.* {
-          proxy_pass      http://{{ template "cortex.fullname" . }}-alertmanager.{{ $rootDomain }}$request_uri;
+          proxy_pass      {{ .Values.nginx.config.upstream_protocol }}://{{ template "cortex.fullname" . }}-alertmanager.{{ $rootDomain }}$request_uri;
         }
 
         location ~ /api/v1/alerts {
-          proxy_pass      http://{{ template "cortex.fullname" . }}-alertmanager.{{ $rootDomain }}$request_uri;
+          proxy_pass      {{ .Values.nginx.config.upstream_protocol }}://{{ template "cortex.fullname" . }}-alertmanager.{{ $rootDomain }}$request_uri;
         }
 
         location ~ /multitenant_alertmanager/status {
-          proxy_pass      http://{{ template "cortex.fullname" . }}-alertmanager.{{ $rootDomain }}$request_uri;
+          proxy_pass      {{ .Values.nginx.config.upstream_protocol }}://{{ template "cortex.fullname" . }}-alertmanager.{{ $rootDomain }}$request_uri;
         }
 
         location = /api/prom/api/v1/alerts {
-          proxy_pass      http://{{ template "cortex.fullname" . }}-alertmanager.{{ $rootDomain }}/api/v1/alerts;
+          proxy_pass      {{ .Values.nginx.config.upstream_protocol }}://{{ template "cortex.fullname" . }}-alertmanager.{{ $rootDomain }}/api/v1/alerts;
         }
 
         {{- end }}
@@ -124,15 +124,15 @@ data:
 
         # Ruler Config
         location ~ /api/v1/rules {
-          proxy_pass      http://{{ template "cortex.fullname" . }}-ruler.{{ $rootDomain }}$request_uri;
+          proxy_pass      {{ .Values.nginx.config.upstream_protocol }}://{{ template "cortex.fullname" . }}-ruler.{{ $rootDomain }}$request_uri;
         }
 
         location ~ /ruler/ring {
-          proxy_pass      http://{{ template "cortex.fullname" . }}-ruler.{{ $rootDomain }}$request_uri;
+          proxy_pass      {{ .Values.nginx.config.upstream_protocol }}://{{ template "cortex.fullname" . }}-ruler.{{ $rootDomain }}$request_uri;
         }
 
         location ~ /api/prom/rules {
-          proxy_pass      http://{{ template "cortex.fullname" . }}-ruler.{{ $rootDomain }}$request_uri;
+          proxy_pass      {{ .Values.nginx.config.upstream_protocol }}://{{ template "cortex.fullname" . }}-ruler.{{ $rootDomain }}$request_uri;
         }
 
         {{- end }}
@@ -141,16 +141,16 @@ data:
 
         # Query Config
         location ~ /api/prom/.* {
-          proxy_pass      http://{{ template "cortex.fullname" . }}-query-frontend.{{ $rootDomain }}$request_uri;
+          proxy_pass      {{ .Values.nginx.config.upstream_protocol }}://{{ template "cortex.fullname" . }}-query-frontend.{{ $rootDomain }}$request_uri;
         }
 
         ## New Query frontend APIs as per https://cortexmetrics.io/docs/api/#querier--query-frontend
         location ~ ^{{.Values.config.api.prometheus_http_prefix}}/api/v1/(read|metadata|labels|series|query_range|query) {
-          proxy_pass      http://{{ template "cortex.fullname" . }}-query-frontend.{{ $rootDomain }}$request_uri;
+          proxy_pass      {{ .Values.nginx.config.upstream_protocol }}://{{ template "cortex.fullname" . }}-query-frontend.{{ $rootDomain }}$request_uri;
         }
 
         location ~ {{.Values.config.api.prometheus_http_prefix}}/api/v1/label/.* {
-          proxy_pass      http://{{ template "cortex.fullname" . }}-query-frontend.{{ $rootDomain }}$request_uri;
+          proxy_pass      {{ .Values.nginx.config.upstream_protocol }}://{{ template "cortex.fullname" . }}-query-frontend.{{ $rootDomain }}$request_uri;
         }
 
         {{- end }}
@@ -160,7 +160,7 @@ data:
         {{- range $org := compact .Values.nginx.config.auth_orgs | uniq }}
         location = /api/v1/push/{{ $org }} {
           proxy_set_header      X-Scope-OrgID {{ $org }};
-          proxy_pass      http://{{ template "cortex.fullname" $ }}-distributor.{{ $rootDomain }}/api/v1/push;
+          proxy_pass      {{ $.Values.nginx.config.upstream_protocol }}://{{ template "cortex.fullname" $ }}-distributor.{{ $rootDomain }}/api/v1/push;
         }
         {{- end }}
         {{- end }}
diff --git a/values.yaml b/values.yaml
index ea87bf5d..b10da422 100644
--- a/values.yaml
+++ b/values.yaml
@@ -1196,6 +1196,8 @@ nginx:
     mainSnippet: ""
     # -- arbitrary snippet to inject in the server { } section of the nginx config
     serverSnippet: ""
+    # -- protocol for the communication with the upstream
+    upstream_protocol: http
     setHeaders: {}
     # -- Optional list of [auth tenants](https://cortexmetrics.io/docs/guides/auth/) to set in the nginx config
     auth_orgs: []