RFlink entities unavailable after restart, until turned on manually in real life

[javicalle]

To persist devices between restarts, they must be declared in the RFLink configuration. Entities added by the automatic_add mechanism will not be available until detected by RFLink.

It seems to me that your RFLink configuration is incorrect.
Devices definitions should not have the platform prefix:

@RolandTwilt

light:
# add the following to the existing light section
  - platform: rflink
    automatic_add: true
    devices:
      afzuiging:  # <-- that one doesn't seems to be a valid RFLink ID
        name: afzuiging washok
      kaku_00004b_5:
        name: test_device

Be carefull with the configuration indentation. It matters.