WiFi restarted frequently

WiFi restarted frequently, shown as below.
2020-4-27, 22:10:56 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 22:10:56 Warning (5) MDD message timeout;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 22:10:56 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 21:55:10 Warning (5) MDD message timeout;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 21:55:10 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 21:54:05 Warning (5) MDD message timeout;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 21:53:19 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 21:53:19 Warning (5) MDD message timeout;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 19:46:28 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 19:45:05 Warning (5) MDD message timeout;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 19:43:14 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 19:43:14 Warning (5) MDD message timeout;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 19:43:14 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 19:41:18 Warning (5) MDD message timeout;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 19:30:23 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 19:21:25 Warning (5) MDD message timeout;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 19:21:25 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 19:21:17 Warning (5) MDD message timeout;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 19:00:20 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 19:00:20 Warning (5) MDD message timeout;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 19:00:20 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 19:00:20 Warning (5) MDD message timeout;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 07:13:35 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 07:12:58 Warning (5) MDD message timeout;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 06:38:30 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=08:36:c9:47:d0:b8;CMTS-MAC=0c:11:67:02:36:3e;CM-QOS=1.1;CM-VER=3.0;
2020-4-27, 06:38:30 Warning (5) MDD message timeout;CM-MAC=08:36:c9:47:d0:b8;CMT

Can anyone help to fix that? Thanks.