Have you resorted to my method of posting and then adding? That is my domain 
Off topic: Hope you had a nice birthday dinner!
I did, thank you, It was a nice evening. 
Sry for the late reply, been busy with other stuff then.
Thanks a lot @texnixe and @jimbobrjames for your help!
Indeed, updated PHP version a now everything works fine.
Btw – will update my show-to-client-workflow with subdomains 
Have a nice day!