I followed this guide to update my old Conbee II to a Thread firmware. Before, i ran the multi pan firmware on my SkyConnect stick. I've since reverted that stick to zigbee only and added the Conbee II in OpenThread Border Router as the Thread device.
The devices i've previously added to matter still react and can be controlled. But adding an Eve Energy doesn't work as it complains about a lack of Thread Border Routers. Anyone got a clue? Resetting the border router and changing the channel didn't yield any better results.