Need help with web connectivity

[DSh1001]

In the overview of myQNAPcloud app there is a red cross next to web connectivity.

Also when I look under
Control Panel --> Network and Virtual Switches --> Overview
it says Internet cannot be reached.

I've enabled automatic port forwarding and am using a fritzbox as router.

Anybody have any hints for me?
Context: I am trying to install the SSH certificate from let's encrypt, but apparently they cannot reach my NAS to check (as far as I understood). Port 80 is enabled and it also says okay in the table of services. I think this is because of the issue witht the web connectivity.