The fact that it's crossed out doesn't mean your not using https. In your screenprint you can see the second statement "Je verbinding met 10.0.0.3 is versleuteld....". If you read what is mentioned above that, it says "De identiteit van deze website is niet geverifieerd. Het servercertificaat komt niet overeen met de URL. Het servercertificaat is niet betrouwbaar. ". The URL you use is 10.0.0.3, the certificate is valid for *.domoticz.com.
You can trick your computer by editing its hosts file (i.e. on Windows: C:\Windows\System32\drivers\etc\). Add this line:
.. and save it. You need to have administrator rights when editing this file. Then open your browser and go to
https://mijn.domoticz.com/. It still says that there is a problem, but you will see that the statement "Het servercertificaat komt niet overeen met de URL" has disappeared.
When you click on "Certificaatgegevens" you will get the info "Dit CA-basiscertificaat wordt niet vertrouwd." It doesn't like the issuer of this certificate. We can solve that.
Click "Certificaatgegevens", select tab "Details" and click "Kopiëren naar bestand...". A wizard starts where you can export this certificate. Click "Volgende", click "Volgende", click "Bladeren" so you can see where the file will be placed, give it a name like "localdomoticz" and click "Opslaan", click "Volgende" (you can see the full path again), click "Voltooien" and a message appears "Het exporteren is voltooid."
Now you can ipmort this certificate in your browser. Looking at your screenprint, you are using Chrome. Start Chrome, open "Instellingen", click "Geavanceerde instellingen weergeven...", click "Certificaten beheren...", click "Importeren", click "Volgende", click "Bladeren" and select the file whe just created, click "Openen", click "Volgende", click "Bladeren" and select "Vertrouwde basiscertificeringsinstanties" and click "OK", click "Volgende", click "Voltooien". Then a warning appears and the system asks if you want to install this certificate, click "Ja". Restart your browser and you will see no crossed out lock anymore.
WARNING:
I must add a warning: if you don't know what you're doing, messing with the system's security settings can be tricky. I can't take any responsibility for problems that arise while following this little tutorial.