Innogy data delayed

I just installed my innogy devices and there’s quite a big time delay: When something changes, it appears almost immediately in the innogy/livisi-app. But then it takes >30seconds until the data arrive in openhab. And this is after I reduced the bridge setting ‘WebSocket idle timeout in seconds’ to 15 (before it was even worse). But reducing it further (to 1) didn’t really help.
The bridge (and its devices) is constantly changing from about 30s offline to 15s online, then back to offline again.
For temperature settings this doesn’t matter too much, but I can’t use my motion detector with such delays …
Any ideas what I could do?