What should I do if AP is offline from AC?

Here are the possible reasons:
a) AP fails to startup
b) AP doesn't work in Fit mode
c) AP does not obtain correct management address when accessing network?
d) AP is disconnected to the AC tunnel address
e)The software version of AP and AC does not match
f) Insufficient license for AC
g) Duplicate AP naming
Troubleshooting steps:
a) AP fails to startup
1. Check whether the AP is powered on normally by checking the AP indicators.
2. If the indicator is off, the AP is not powered on successfully.
3. If the AP indicator is always flashing green which means that the AP main program may be lost. At this time, it is recommended to prepare the configuration line to restore the main program.
b) AP not working in FIT mode:
It is recommended to log in CLI of device and enter the command 'show ap-mode' to confirm.
c) AP does not obtain the correct management address when accessing the network:
1. Check whether the management IP of the AP in the current wireless deployment network plan is automatically obtained or manually configured.
2. If it is manually configured, it is recommended to log in to the AP through the console line to check whether there are ACIP and APIP configurations in the configuration, and check whether the configured IP address is correct.
3. If it is obtained automatically, it is recommended to use the replacement method to test, replace the PC (the network card is changed to automatic obtainment) with the AP access switch to test whether the address is obtained successfully. If the address cannot be obtained or is obtained incorrectly, check the switch configuration.
4. When the tunnel addresses of the AP and the AC are mutually accessed across Layer 3, it is also necessary to pay attention to whether the option 138 field is correctly configured on the address pool of the AP, and to determine the method, log in to the AP to view the ''show capwap client state'. If it is determined that the acip is wrong, you need to log in to all the devices in the address pool of the AP, and change option 138 in AP DHCP.
d) AP is disconnected from the AC tunnel address:
1. Check whether the AP and AC tunnel addresses are connected. First, confirm the tunnel address of the AC. By default, the AC's loopback 0 address is used as the tunnel address. For more details, you can log in to the AC and use 'sho ac-con'' to view the localIpAddr.
2. After confirming the tunnel address of the AC, log in to the AP with the correct IP address and ping the tunnel address of the AC to determine whether it can be pinged successfully.
3. If it is inconvenient to log in to the AP, you can use a computer to replace the AP access switch, and ping the AC tunnel address on the computer to check whether the communication is successfully.
e) The software versions of the V AP and AC do not match:
1. Version 10.x has very high requirements on the version matching between the AP and the AC. It needs to be completely consistent. The inconsistency may cause the AP to not go online.
2. Version 11.x. For most versions, if both the AC and AP are in version 11.x, the AP may go online on the AC.
3. Determine the software versions of the AC and AP, and check the System software version information by logging into the AC and AP show ver respectively.
f) Insufficient license for AC:
The license of the AC is the number of authorizations to manage the AP, which can be confirmed by logging in to the AC and running 'show ac-con'
WS6008#show ac-config
AC Configuration info:
max_wtp: 224
sta_limit: 7168
license wtp max : 32
license sta max: 7168
single wtp max: 224
virtual ac max : 4
whole wtp max : 224
serial auth: Disable
password auth: Disable
certificate auth : Disable
Bind AP MAC: Disable
AP Priority: Disable
supp_psk_cer : Disable
ac_name : Ruijie_Ac_5e406c
ac location: AC_LOCATION
permission manage: Disable
AC State info:
sta_num : 0
act_wtp: 1
localIpAddr : 172.26.5.132
localIpAddr6 :
current wtp max : 224
used wtp :1.0(0 eight 0 four 0 two 1 normal 0 half 0 zero)
//
The currently used license is 1
remain wtp : 3 eight 7 four 15 two 31 normal 62 half 447 zero
//
Check the number in front of 'normal' , if it is 0, it means that the current license has been used up
HW Ver :1.41
SW Ver : AC_RGOS 11.9(6)W1B1, Release(09180101)
Mac address: 5416.515e.406c
Product ID : WS6008
NET ID : 9876543210012345
NAS ID : 5416.515e.406c
Tunnel Mode : hybrid
g) Check if AP is renamed
Log in to the AC and run 'sho ap-con su deny-ap' to check whether the AP is offline because it is stuck in the conflict state. If so, there may be renaming. Log in to the AC and 'show ap-con run' to check.