You could change the login method to local. So you would be able to login to the webadmin by using a local user. Then you have login to the webadmin and you can go on with debuging.
Login to console. Edit /etc/wfe/conf/proxyauth.ini
Goto the section [webadmin_methods]. Add the word "local". This enables local users to login to webadmin. Then add the word "admin" to the section [webadmin_users]. I assume the user admin exists on your system. Otherwise use a user which exists.
Now you should be able to login to webadmin.
If that still does not work, the Astaro User Authentication deamon (AUA) might not run. This would require further investigations. Just post a message, if you still need help.
I had this effect after the update, when i start a up2date pattern update. then i can't connect for 6-10min to the webadmin and the whole www. i'm about to go to the Box and kick it just wait and try again, thats my answer... when this don't work...i don't know...
Please have a look into the aua.log (User Authenticaiton Daemon). Are there any errors at the moment you try to use LDAP? Is the process 'aua' running (Webadmin -> Reporting -> Advanced -> Process List).
If the log does not help, try to enable debuging for aua: Edit /etc/wfe/conf/aua_main_config.ini Add the line "debug = 1" AND A NEW LINE. Restart aua: /etc/rc.d/aua restart
Now the log should be more verbose.
Also you could try to make a manual ldapsearch. If debuging is enabled, you should see the ldapsearch, Astaro makes automatically at the moment you try to authenticate. This ldap search can be made manually. Just type in the command you see in the log manually: 'ldapsearch ....' Note: aua caches! So you might need to restart aua in order to get the needed logging.
Same problem: after V5.203 no login possible with the following message after I entered credentials in webadmin: Internal system error: "The internal authentication daemon could not be reached. Please reboot the system. If the problem persists, please contact your vendor" I use only local authentication and I have the same problem on 2 ASG120 after the upgrade. Please tell me how to fix it.