https://community.cisco.com/t5/wireless/ap-doesn-t-join-the-wireless-controller/m-p/3907978#M203117 The error message of those screenshots are very self-explanatory. Wed, 14 Aug 2019 10:06:10 GMT Leo Laohoo 2019-08-14T10:06:10Z https://community.cisco.com/t5/wireless/ap-doesn-t-join-the-wireless-controller/m-p/3907926#M203116 <P>I installed 20 APs but I can only see 10 of the APs joining my controller. 10 other APs failed to join.&nbsp;</P><P>See the error shown.&nbsp;</P> Mon, 05 Jul 2021 17:51:29 GMT https://community.cisco.com/t5/wireless/ap-doesn-t-join-the-wireless-controller/m-p/3907926#M203116 tosjerr 2021-07-05T17:51:29Z https://community.cisco.com/t5/wireless/ap-doesn-t-join-the-wireless-controller/m-p/3907978#M203117 The error message of those screenshots are very self-explanatory. Wed, 14 Aug 2019 10:06:10 GMT https://community.cisco.com/t5/wireless/ap-doesn-t-join-the-wireless-controller/m-p/3907978#M203117 Leo Laohoo 2019-08-14T10:06:10Z https://community.cisco.com/t5/wireless/ap-doesn-t-join-the-wireless-controller/m-p/3908101#M203118 <P>I have tried analyzing the problem but doesn't seem to know what to do about it.&nbsp;</P> Wed, 14 Aug 2019 13:41:02 GMT https://community.cisco.com/t5/wireless/ap-doesn-t-join-the-wireless-controller/m-p/3908101#M203118 tosjerr 2019-08-14T13:41:02Z