Hi!
I do have a IKEA Trådfri-lamps and remote. Can I pair it directly to the lamp (to be controlled even if Home Assistant are down) AND to the Conbee via ZHA? Or does all Zigbee communication have to go over the Conbee-network?
Why? I want the lamp and remote to work even it the gateway are down. And for some curiosity… 
No you can’t.
Thanks! I kind of understand why! 
I’m sure it can. See the second video on linked page bellow.
Smart bulbs and remote controllers can be paired together without need of having any gateway. It works for Philips Hue and IKEA TRÅDFRI.
Don’t know about ZHA, but you sure can using Zigbee2MQTT
A bit confused here…
I don’t have IKEA Gateway in the system. Only HA and Conbee2 in the system.
Check out binding in ZHA.
How I did it in Zigbee2MQTT :
Pair the E1743 to the coordinator. Create a group in Zigbee2MQTT. Put my bulb in the group in Zigbee2MQTT. Bind the E1743 to the group. Now the E1743 controls the bulb directly, and I can still use lovelace and automations in HA to control the bulb.
See
under binding.
Can you also react on button presses of the remote?
Yes I can.
Thanks for all wisdom!
I do use ZHA, can the groups be created there or is it a Zigbee2MQTT feature only?
If ZHA is a less feature rich alternative, can I change to Zigbee2MQTT easily without having to recreate the Zigbee network (reset and include all nodes)? I have Mosquitto running and used by HA already. I run HA on Ubuntu + Docker.
Interesting! 
Need to check it out!
I don’t use ZHA (I use deconz), however I can tell you that you need to repair every device if you switch to ZigBee2MQTT.
Did you ever come to a solution for this? If so I am really interesting to hear about it.
In Deconz, if I remember correctly, you can do it either by putting the bulb in the remote “group” (though I had issues with it sometimes not creating the group automatically, so had to mess with it using the api), or by binding the clusters directly (in deconz you can do so via the vnc gui). From what I read, the same should be possible in ZHA (either via groups or via cluster binding) - but can’t say how exactly as I am not running them.
For the on/off square-dimmer from IKEA i was able to bind to a IKEA wall plug.
But I have not figured out how to bind to a IKEA lama for controlling it (on/off/dim).
Also, note I have actually not tested it with HA offline, but I guess the communication are not handeled by HA / Conbee 2.
This Blueprint simplifies the automation when I rely on HA:
I have successfully been able to control my Ikea lamp (Floalt) from both the Trådfri remote and from HA following the suggestions in this thread. Now an issue has however occurred. I can still control the color temperature from both remote and HA but the when changing the color temperature using the remote does not reflect in HA. Anyone else experiencing the same and/or has a suggestion for resolving this?
FYI, binding and unbinding is explained in ZHA documentation but please feel free to improve that documentation to make it more clear and easier to understand as well as explain the steps needed:
https://www.home-assistant.io/integrations/zha#binding-and-unbinding
