Cant add my forum in DiscourseHub iOS app

Hi

When trying to add my forum in DiscourseHub iOS app i get this error:
domain.tld was not found!
This is in nginx log:
a.b.c.d - - [07/Nov/2022:19:13:46 +0100] "HEAD /user-api-key/new HTTP/2.0" 400 0 "-" "Discourse/381 CFNetwork/1399 Darwin/22.1.0"

Also i have default user api settings.


And my forum is behind nginx reverse proxy.
Relevant config:

location / {
        proxy_pass http://127.0.0.1:8080/;
        proxy_cache my_cache;
        proxy_read_timeout 90;
        proxy_redirect http://localhost:8080/ https://domain.tld;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header Host $http_host;
        proxy_redirect off;
        # Socket.IO Support
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
}

Does anyone have any idea how to fix this issue?

Thanks for help,
David