I have looked on different forums and it's quite confusing. So if someone could clarify, then thanks in advance.
Cisco AP connected to switch, port in trunk mode.
Config of port on switch:
switchport trunk encapsulation dot1q
switchport trunk native vlan 303
switchport trunk allowed vlan 1,303,313,353
switchport mode trunk
storm-control broadcast level 60.00
storm-control multicast level 60.00
storm-control action shutdown
storm-control action trap
spanning-tree bpduguard enable
This is a config not set by myself and what is bothering me most is the last line. "spanning-tree bpduguard enable". This setting puts another AP in "err-disable" mode (not this one).
286229: Nov 6 10:59:39.288 CET: %SPANTREE-5-TOPOTRAP: Topology Change Trap for vlan 1
286233: Nov 6 11:01:45.872 CET: %SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on port Fa0/3 with BPDU Guard enabled. Disabling port.
286234: Nov 6 11:01:45.872 CET: %PM-4-ERR_DISABLE: bpduguard error detected on Fa0/3, putting Fa0/3 in err-disable state
286235: Nov 6 11:01:46.896 CET: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to down
286236: Nov 6 11:01:47.894 CET: %LINK-3-UPDOWN: Interface FastEthernet0/3, changed state to down
So I disabled "spanning-tree bpduguard". Problem solved. BUT, didn't I disabled an important anti-loop rule here? Although the network is still running fine. And the other AP's have this enabled, but aren't going into "err disable".
This is a trunk port, maybe this rule is more applied on access ports?