Cannot get EVBox Elvi to work

[AtariAndre42]

I have had my configuration actually working before, but after paying for a lifetime token and the latest update, I cannot get my EVBox Elvi to validate whatever I try.
There is usually a time-out or I get "Request failed with status code 502".
Even when I select "Save anyway" I get a "create failed" message.
I'm clueless and desperate and about to give up on the whole thing...