Device connection through https fails

The webif https connection works well, only the client fails to connect.
I am mapping port 55056 to port 5055.

<IfModule mod_ssl.c>
        <VirtualHost *:443>

                ServerName 192.168.7.222
                ServerAdmin webmaster@localhost

                DocumentRoot /var/www/html

                ProxyPass /api/socket ws://localhost:8082/api/socket
                ProxyPassReverse /api/socket ws://localhost:8082/api/socket

                ProxyPass / http://localhost:8082/
                ProxyPassReverse / http://localhost:8082/

                SSLEngine on
                SSLCertificateFile /etc/apache2/ssl/apache.crt
                SSLCertificateKeyFile /etc/apache2/ssl/apache.key

        </VirtualHost>


 <VirtualHost *:55056>

                ServerName 192.168.7.222
                ServerAdmin webmaster@localhost

                DocumentRoot /var/www/html

                ProxyPass / http://localhost:5055/
                ProxyPassReverse / http://localhost:5055/

                SSLEngine on
                SSLCertificateFile /etc/apache2/ssl/apache.crt
                SSLCertificateKeyFile /etc/apache2/ssl/apache.key

        </VirtualHost>

</IfModule>

When i call https://myurl.com:55056 in the browser a connect in the traccar-server logfile is shown:

2017-12-10 15:03:57  INFO: [AAD67EF2] connected
2017-12-10 15:03:57 DEBUG: [AAD67EF2: 5055 < 192.168.7.222] HEX: 474554202f20485454502f312e310d0a486f73743a2031393
22e3136382e372e3232323a35353035350d0a557365722d4167656e743a204d6f7a696c6c612f352...

I am using Traccar Client 5.5 on Android where i put in https://myurl.com:55056 to connect to, but the connect isn't visible in the logfile and the App
tells me that the connection has failed.
If I switch back everything to unencrypted traffic again, everything works as expected.

What's on the status screen in the app?

How come you don't have a DNS server name? Is certificate valid?

The status screen on the app says: "transfer failed"

Does the app check for a vaild certificate? I use self signed certificate.

The Server is running at home on an ubuntu machine, where the ports are forwarded to the outside.

Obviously you need a valid certificate.

Would it be enough to import the certificate on the android device?

I'm not sure. Possibly.

Thanks a lot, i will try, Could you tell me please how the app checks if a certificate is valid or not?

It doesn't. Android system does it.

A certificate from "Let's encrypt" did the trick.
I have to try if it would also work for the "Traccar Manager"-App.