Hi Cornel,
There is setting on the AP for the LED. If this setting is set to Identify the LED will flash two or four times every second. Check if the Identify option is enabled.
Configuring Operational Mode for One AP:
To configure the AP LED operational mode when configuring an individual wireless AP:
1 From the top menu, click AP > APs.
2 In the AP list, click a wireless AP (not the checkbox).
The AP Configuration page displays with the AP Properties tab exposed.
3 On the AP Properties tab, click Advanced .
4 In the LED field, select an LED operational mode.
Regards
Sandeep