How to troubleshoot when the CAPWAP tunnel fails to establish？

Phenomenon:
The communication between the AP and AC is abnormal.
Possible Causes:   
(1)  The AP did not obtain the IP address.
(2)  The AP
did not obtain the option 138
(3) The AP
cannot ping through the AC to establish a tunnel address
(4)  CAPWAP udp ports 5246 or 5247 are discarded or filtered by the intermediate device
Phenomenon:
The AC and AP are abnormal
Possible Causes:
(1) The AC CPU is too high to process the AP going online

show cpu

(2) The ac license is insufficient.

show ac-config
show license
show ap-config summary

Command display example
WS5302#sh ac-config
AC Configuration info:
max_wtp :32 // wtp limit Number of aps that can be connected to ac-con
sta_limit :1024
license wtp max: 32 // Number of aps supported by ac
license sta ma:1024
serial auth : Disable
password auth: Disable
certificate auth: Disable
supp_psk_cer: Disable
r_mac: Enable
da_dtls: Disable
ac_name: Ac_001aa917151c
udp_lite : UDP
ECN_Sup : Disable
mtu :1500
ap_sw_ver :
ac location :Ac_COM
ac_ipv4_num : 0
ac_namewp_num:0
AC State info:
sta_num :0
act_wtp :1
WS5302#show license // View the current license
Serial Number: 9071FH4280024
No. Activation Key AP Number
-------------------------------------------------------
-------------------------------------------------------
Total 32 access points are supported.
WS5302#show ap-config summary
========= show ap status =========
Radio: E = enabled, D = disabled, N = Not exist
Current Sta number
Channel: * = Global
Power Level = Percent
Online AP number: 1 // Number of online aps
Offline AP number: 0
AP Name                                  IP Address      Mac Address    Radio 1             Radio 2             Up/Off  time   State
---------------------------------------- --------------- -------------- ------------------- -------------------  ------------- -----
a94e.d529 192.168.100.3 001a.a94e.d529 E 0 11* 100 E 0 157* 100 0:03:09:17 Run
ac and ap versions have large spans (2b15, 2b117 and 1b19p2,10.x and 11.x).
The ap name is the same
19 16:37:19: CD-AC4 %APMG-6-AP_ADD:  Add AP(1414.4b5d.03af) fail. Online-AP(1414.4b5d.097f) with same name(XS10A4-1) has exist in this AC-- Changes the name of an online ap
Collect the following information and contact TAC
1) Collect the following information on the AC:
show version
show running
show ac-config
show license
show ap-config summary
show capwap sta
show cpu
show memory
show ip route
show ip interface brief
2) Collect the following information on the AP:
show version
show ap-mode
show capwap sta
show ip route
show log
show ap-statistic aclist (View ap to obtain option 138 addresses)
show capwap client state (11.x)