Obviously something has being changed. I have a Fritz!Box 7490 that has been working seemlessly with an eBlocker running on Raspi3 via eBlocker mobile.
Now, I have configured my eBlocker as a brand new one from the scratch.
But now, it is to me impossible to configure eBlocker mobile. I use - as before - my dynamic DNS address namesomeoddletters.myfritz.net. UPnP is being activated on Fritz!box. So in next step, I let try eBlocker to self assign the appropriate ports 1194 to 1194. That is calling success. But then, when I push the button "test connection" it's calling "FAILURE". I do not know, why.
Is there something being known about eBlocker mobile won't work with Fritz!Box 7490 by Fritz!OS 7.29?
… and self assigning ports must not being activated. That did the trick. Thank you.