AP Failed to Connect The Internet

There is also a question discussed hotly,  AP failed to connect the internet and then make up? Everybody can show your ideas the following. The AP of the 2504WLC 1602 can be registered commonly, but when I check the diary, AP is disconnected and reconnected.
The main logs usually are as follows:

37
Mon Mar 25 09:28:06 2019
AP’s Interface:1(802.11a) Operation State Up: Base Radio MAC:00:6c:bc:c3:f8:80 Cause=Unknown Reset Status:NA
38
Mon Mar 25 09:28:06 2019
AP’s Interface:0(802.11b) Operation State Up: Base Radio MAC:00:6c:bc:c3:f8:80 Cause=Unknown Reset Status:NA
39
Mon Mar 25 09:28:06 2019
AP’s Interface:0(802.11b) Operation State Up: Base Radio MAC:00:6c:bc:c3:fa:70 Cause=Unknown Reset Status:NA
40
Mon Mar 25 09:28:05 2019
AP’s Interface:1(802.11a) Operation State Down: Base Radio MAC:00:6c:bc:c3:fa:70 Cause=Radio interface reset. Status:NA
41
Mon Mar 25 09:28:05 2019
AP ‘APe00e.daa6.508f’, MAC: 00:6c:bc:c3:f8:80 disassociated previously due to Link Failure. Uptime: 4 days, 22 h 36 m 31 s . Reason: Capwap WTP Event request.
42
Mon Mar 25 09:28:05 2019
AP ‘APe00e.daa6.50ae’, MAC: 00:6c:bc:c3:fa:70 disassociated previously due to Link Failure. Uptime: 4 days, 23 h 47 m 32 s . Reason: Capwap WTP Event request.

The grounds maybe are:
1. A problem with its hardware.
2. A problem with the wireless channel. Often the channels are not separated.
3. The influence of cellular.
4. The insufficient bandwidth is not enough.