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Can't connect to with XMPP-client

I just tried to connect to my account on with but got the error message "Incompatible server"? should be a real XMPP client? The information about also says:

"All (friendly) creatures welcome! Free registration. Server located in Germany. As a registered user on Nerdica.Net you are also able to use XMPP (Jabber) under the same address and with your password. Get the best of free and open networks at Nerdica.Net! :-)"

Hmmm, it should work. Have you tested the web interface on and logging in with your "" and your password?

Hmmm, strange... when checking server status on it shows that everything is 100% ok... the compliance tester is using same kind of authentication as every other user as well. And it is from the author of, so I expect that it will use the same methods to authenticate as the client on Android does.
But when the web interface is working, I guess it's more like a client issue then. Can you check if is using TLS on port 5222 or if it is trying to use SSL on port 5225?

Currently I see legacy SSL port is only listening on IPv6:
root@jabber:~# netstat -tulpen | grep 5225
tcp6       0      0 :::5225                 :::*                    LISTEN      0          2488867    24419/slt

No idea why "slt" is not listening on IPv4 at the moment, but when you are on IPv4-only network, this is most likely the reason of your issue.
So, either try IPv6 or convince conversations to use TLS on port 5222...

Now it works for me to connect with android app without any changes. Just using the same stored password and username as I did before. Very strange.

And now I have the same problem again with with "incompatible server" message on my Android phone...

Try again. "slt" is now listening to IPv4 socket...

it still says incompatible server

I'm running out of ideas... the compliance tester of says, 100% ok and you can connect with other clients such as the web interface on, so I think it's a client issue and you should contact Daniel Gultsch about that.
Maybe you can provide some more information, like IP addresses and such... please send me the information directly using the XMPP web interface on

Please try again... I'm now online and reachable...

After help from @Ingo Jürgensmann I think we can be pretty sure the problem is in the client in connection with the nerdica server. When I try to connect with another client, Xabber for Android, it works fine.

Ok, I checked back with Daniel Gultsch on Twitter... in his opinion the problem might be that I'm using "slt" for proxying SSL connections to TLS and TLS is expecting STARTTLS command... So, the compliance tester is happy with the current setup, but the real client is not.

For some unknown reasons (at the moment) the configuration does not work as documented (legacy_ssl_ports for Prosody)...