无线AP上不了线

一台POE接入交换机下接4个AP，相同型号，只有1个AP在线，其它3个AP无法上线，一直重启，通过con口查看AP启动过程如下：

BootWare Validating... 

Press Ctrl+B to access EXTENDED-BOOTWARE MENU...

 Loading the main boot and system image files... 

The system image does not exist! Loading the backup boot and system image files... The image does not exist! Booting image fails! Trying to get the IP address from the DHCP server...... DHCP server's IP address is 10.100.102.254 Client's assigned address is 10.100.102.40 DNS domain name got from DHCP server is DNS server's IP address is 0.0.0.0 Default Gateway's IP address is 10.100.102.254 This client's subnet mask is 255.255.255.0 The length of option 43 is: 9 Change State : Idle to Broadcast Discovery Change State : Broadcast Discovery to Unicast Discovery Use Option 43: Getting AC's IP Address 10.100.103.254 Change State : Unicast Discovery to Join Change State : Join to JoinAck Change State : JoinCfm to Image Download Change State : Idle to Broadcast Discovery Change State : Broadcast Discovery to Unicast Discovery Use Option 43: Getting AC's IP Address 10.100.103.254 Change State : Unicast discovery to Sulking Can't download the image from network, please check the network settings The system will reboot

上边过程都正常，到最后显示Can't download the image from network, please check the network settings The system will reboot

可是可以确定网络是通的