Hi all,
I have added a self-made lightstripe to OH. Instead of programming everything from scratch, I used ESPHome 
ESPHome supports Homeassistant, and I found the stripe in the Inbox indeed 
When I add the Thing to OH, I do not see any channel available, and OH also logs the following message
==> /var/log/openhab/openhab.log <==
2022-01-30 21:50:19.303 [WARN ] [re.thing.internal.ThingFactoryHelper] - Could not create channel 'ESPlightstefi_5Fbed_5Flamp#color', because channel type 'mqtt:ESPlightstefi_5Fbed_5Flamp_color' could not be found.
2022-01-30 21:50:19.306 [WARN ] [re.thing.internal.ThingFactoryHelper] - Could not create channels for channel group 'ESPlightstefi_5Fbed_5Flamp' for thing type 'mqtt:homeassistant_98f4abcd5b2f:Localhost:98f4abcd5b2f', because channel group type 'mqtt:ESPlightstefi_5Fbed_5Flamp' could not be found.
Looking to mosquitto it seems to have the right subscription (but I am not an expert)
openhabian@openhabHost:~ $ mosquitto_sub -v -u openhabian -P <pwd> -t homeassistant/light/#
homeassistant/light/night-lamp-stefi/stefi_bed_lamp/config {"schema":"json","clrm":true,"supported_color_modes":["rgb"],"brightness":true,"name":"Stefi Bed Lamp","stat_t":"night-lamp-stefi/light/stefi_bed_lamp/state","cmd_t":"night-lamp-stefi/light/stefi_bed_lamp/command","avty_t":"night-lamp-stefi/status","uniq_id":"ESPlightstefi_bed_lamp","dev":{"ids":"98f4abcd5b2f","name":"night-lamp-stefi","sw":"esphome v2021.12.2 Jan 30 2022, 10:15:28","mdl":"d1_mini_pro","mf":"espressif"}}
Perhaps confirmed by the UI 
UID: mqtt:homeassistant_98f4abcd5b2f:Localhost:98f4abcd5b2f
label: Night Lamp Stefi
thingTypeUID: mqtt:homeassistant_98f4abcd5b2f
configuration:
topics:
- light/night-lamp-stefi/stefi_bed_lamp
basetopic: homeassistant
bridgeUID: mqtt:systemBroker:Localhost
Still, the only channel available does not seem to control the light
While I can control the light through the server running locally on the microcontroller.
Any idea where I can start debugging the setup?
Thanks!
Max