I have a RB2011UiAS with 6.48.6 and basic VLAN internet gateway/firewall functions

I want to use these as CAPsMAN AP:
- RB951Ui-2nD, hAP
- RB941-2nD-TC, hAP-Lite TC

If I connect one of these in CAPS boot mode to the RB2011 (access port vlan3) directly, my whole network goes down.
When I remove it, the network recovers.

If I do the same behind a trunked switch (access port vlan3), everything is fine.

What could the problem be?

What do you mean the whole network goes down ?

I feels like a flood... all my clients lose network connection.

Did you try to manually configure the CAPs ?