OpenWB SE via Modbus starts charging delayed (and stops for no obvious reason)

[alien0matic]

Hi,
I just got my OpenWB SE 11kW wallbox and installed it. I want to control it via evcc which is running as an AddOn in Home Assistant. I was using evcc that way with a Shelly plug and the normal wall outlet charger from VW for 2 months with no problem. It started charging right away when I enabled it.
Now I have the OpenWB SE configured as a secondary and Modbus enabled.
If I now switch to fast loading it shows it is charging with 3.5kW (the hybrid can't do more), but the Kostal Smart Energy Meter isn't showing any power being drawn. That can go on for minutes.
Even if it started charging and I saw the power, it happens, that it just stops for no reason and the cycle starts again.

What is the happening here? Why is there such a big delay?

What is the correct way to use the OpenWB with evcc? I've read somewhere that one should use HTTP but the HTTP for OpenWB Pro and OpenWB Series 2 don't work. Did they change something and some work needs to be done here to work with the newer SE?