Updated Server Diagnostics Troubleshooting (markdown)

Server-Diagnostics---Troubleshooting.md

@@ -58,7 +58,7 @@ tcp        0      0 127.0.0.1:5232          0.0.0.0:*               LISTEN
 tcp6       0      0 ::1:5232                :::*                    LISTEN      4117/python3       
 ```
 
-# Connection tests
+# Connection tests (plain-text)
 
 Direct connection tests, for tests via reverse proxy see [Reverse-Proxy-Diagnostics-Troubleshooting](Reverse-Proxy-Diagnostics-Troubleshooting)
 
@@ -152,3 +152,55 @@ Successful result:
         <displayname>Feiertage Bayern</displayname>
         <C:calendar-description>Feiertage Bayern</C:calendar-description>
 ```
+
+# Connection tests (SSL)
+
+## Test connection using "OpenSSL c_client"
+
+```bash
+openssl s_client -connect localhost:5232
+Connecting to 127.0.0.1
+CONNECTED(00000003)
+...
+    Verify return code: 19 (self-signed certificate in certificate chain)
+    Extended master secret: no
+    Max Early Data: 0
+---
+read R BLOCK
+```
+
+Hit CTRL-C to terminate in case of successful connect.
+
+
+## Test request using "curl"
+
+### initial test
+
+Add option `-v` in case of an issue, `-k` disable certificate validation
+
+```bash
+curl -k -I  https://localhost:5232/.web/
+HTTP/1.0 200 OK
+Date: Sat, 08 Mar 2025 15:51:34 GMT
+Server: WSGIServer/0.2 CPython/3.13.2
+Content-Type: text/html
+Last-Modified: Sat, 08 Mar 2025 14:43:26 GMT
+Content-Length: 9397
+```
+
+### test as real client
+
+Request without `-k` must be successful (usually, if configured certificate is issued from a public known CA), otherwise normal client will not accept the TLS connection
+
+```bash
+curl -I https://CDAV.DOMAIN.EXAMPLE/.web/
+HTTP/1.1 200 OK
+Date: Sat, 08 Mar 2025 15:56:48 GMT
+Server: WSGIServer/0.2 CPython/3.9.21
+Content-Type: text/html; charset=UTF-8
+Last-Modified: Sun, 26 Jan 2025 07:15:14 GMT
+Content-Length: 8669
+Vary: User-Agent
+```
+
+