normally connecting Matter Devices in Home Assistant should be really easy. You have to go the Devices view in your Home Assistant app of your Android phone:

(I’m not sure, if that bug also exist on iPhone)

if you see above screen to long, you have to set your device to connection mode. read the device manual

and then, i assumed a success message, but received that …

hmm, what now. i tried several things: resetting the network, disconnected the 5 Ghz VLAN, reseted the firewall, changed several settings in Home Assistant, rebooted Home Assistant multiple times, Factory Reset of the Matter device – nothing worked

Then i tried to connect the device to Google Home and … bang … it was connected to Google Home, so it was not the device and not the network, it’s an issue with the Matter integration of Home Assistant. strange thing, some days earlier, i could connect devices from the same model to Home Assistant. to be honest, i’m to lacy to open an Issue in GitHub and then wait till somewhen, so i prefer this work-around:

now you can share that device with Home Assistant:

in Google Home go to the Settings Screen and select the new Matter device:

if you have multiple Home Assistant instances on your phone you receive the selection screen:

and … bang … the device is connected to Home Assistant

if you want, you can add it now to a second Home Assistant instance or remove it from Google Home