diff --git a/Reverse-Proxy-Diagnostics-Troubleshooting.md b/Reverse-Proxy-Diagnostics-Troubleshooting.md
index 129e8c7..2855adc 100644
--- a/Reverse-Proxy-Diagnostics-Troubleshooting.md
+++ b/Reverse-Proxy-Diagnostics-Troubleshooting.md
@@ -188,11 +188,21 @@ ngrep -d lo port 5232
 
 # Authorization Header suppressed
 
-## Apache + WSGI
+## Reverse Proxy
+
+Required option to use user authentication of _radicale_:
+* Apache: (nothing-to-do, not blocked by default)
+* nginx: `proxy_pass_header Authorization`
+
+See also example configurations:
+* https://github.com/Kozea/Radicale/blob/master/contrib/nginx/
+
+## Apache+WSGI
 
 Required option to use user authentication of _radicale_: `WSGIPassAuthorization On`
 
-See also example configuration: https://github.com/Kozea/Radicale/blob/master/contrib/apache/radicale.conf
+See also example configurations:
+* https://github.com/Kozea/Radicale/blob/master/contrib/apache/
 
 # MOVE not working
 
@@ -218,6 +228,8 @@ Check for headers passed to _Radicale_
 See also
 * https://github.com/Kozea/Radicale/blob/master/contrib/apache/radicale.conf
 
+Note: `X-Forwarded-Host` is added by default
+
 ```
 		RequestHeader    set X-Forwarded-Port "%{SERVER_PORT}s"
 		RequestHeader    set X-Forwarded-Proto expr=%{REQUEST_SCHEME}
@@ -230,4 +242,21 @@ See also
     proxy_set_header  X-Forwarded-Host $host;
     proxy_set_header  X-Forwarded-Port $server_port;
     proxy_set_header  X-Forwarded-Proto $scheme;
-```
\ No newline at end of file
+```
+
+# Connection not working or flapping
+
+In case connection from reverse proxy towards _Radicale_ is not working or flapping check
+* SELinux configuration above
+* Listen socket of _Radicale_ matches ProxyPass host configuration
+
+| **System** | **ProxyPass** | **Radicale server/host** | **Expected Result** |
+| -- | -- | -- | -- |
+| IPv4-only | 127.0.0.1 | 127.0.0.1 | ok |
+| IPv4-only | localhost | 127.0.0.1 | ok |
+| IPv4-only | 127.0.0.1 | localhost | ok |
+| IPv4-only | localhost | localhost | ok |
+| IPv4+IPv6 | 127.0.0.1 | 127.0.0.1 | ok |
+| IPv4+IPv6 | localhost | 127.0.0.1 | flapping |
+| IPv4+IPv6 | 127.0.0.1 | localhost | ok |
+| IPv4+IPv6 | localhost | localhost | ok |
\ No newline at end of file