Added user login issue solution. If .ssh folder has too wide permissions, login is not possible.

docs/admin/troubleshooting.md

@@ -17,13 +17,28 @@
 
 ## User management
 
+### A newly added user has no access
+
 **Issue**: A user was added to the **dl-iet-cluster@ost.ch** group,
 but still does not have access to the cluster after days.
 
+#### Case 1
+
+In case the user was successfully added and the home folder exists, check the permissions of the `.ssh` folder.
+If permissions are too wide, i.e. not `drwx------`, set it accordingly
+
+```shell
+    $ chmod 700 .ssh
+```
+
+The user should now be able to log in.
+
+#### Case 2
+
 Check if the user is really part of the group
 
 ``` shell
-groups <user_name>
+    $ groups <user_name>
 ```
 
 shows a list of groups the user belongs to.
@@ -50,6 +65,7 @@ If positive, check whether the user is in the `group` file
 ```
 Remove the user `<user_name>` from the file and try to log in again.
 
+
 ## Intelligent platform management interface (IPMI)
 
 A set of tools to boot and reset nodes without the need of a running