Product and Software: This article applies to all Aruba controllers and ArubaOS 3.1 and later.
The APs are intermittently bootstrapping. If you reboot the APs and controller, the issue is not resolved.
These APs are connected over the Internet with an IPsec-based virtual private network (VPN) solution from Juniper NetScreen firewall. The ScreenOS version is 5.4r8.
The root cause is that the GRE packets were erroneously dropped by the VPN gateway.
To work around the issue, clear the GRE sessions on the VPN gateway.