Joining the family account does not work

[76joda]

Plan: Family

Free/Premium: Premium 

Country: Germany

Device

(Samsung Galaxy Note 3)

Operating System

(Android 5)

My Question or Issue

I confirmed my current address today after logging in to Spotify.
Then I invited my son, i.e. sent him the link created by Spotify via signal messenger.
He opened the link, logged in to Spotify (he already had a free account) and confirmed his address manually. Spotify says: You have to live at the same address and it looks like he is trying to enter Spotify Premium Family from another country.
???
We are sitting in the same room and using the same WLAN access...
New attempt: I allowed Spotify on his cell phone to determine the location: Same error message...
I don't know exactly how the location query works and I fully understand that Spotify checks this on a family account. But the check should also work.

It says in the FAQs that if you can't add yourself to the family account, ask the account manager (me) to send a new invitation link. I tried that, but how does it work? The link will be shown automatically by Spotify, I can't change it. I have logged out and logged in again - the link remains the same.

What do we have to do so that my son (yes, he lives with me) can join the family account?

[Luan]

Hey, @76joda 
Welcome to Spotify Community and thanks for reaching out here!

Sorry to hear that is happening to you... 

In this case, firstly, I recommend that you resend the link to your son using another method (preferentially by email) and ask him to open it using another device that doesn't be to one you've used to send the invitation. And, if possible using the incognito mode of his preferred browser. 

Follow these steps again and let me know if that works.

Regards,

hezorg