5cm is close, 2m is not 
After zigbee ever has been reset (after fw v5.x.x that is) it’s best practice to pair it near the router device closest to the lamp’s location.
How many devices do you have in total?
(Athom’s advice = max. 35 to 40
Some owners reported ~50 as the workable limit)
If it runs fine, don"t touch it I would say.
To find out if zigbee has been reset:
Goto https://tools.developer.homey.app/tools/zigbee and look for “Network Key”
If that is not equal to “01:03:05:07:09:0b:0d:0f:00:02:04:06:08:0a:0c:0d” it has been reset most probably.
