Also noticed this:
Sep 30 14:47:43 KERNEL(Birmingham-AP01-23366@xx.xx.xx.16): [277928.401101] dfs_init_radar_filters: dfsdomain=2, numradars=9, numb5radars=0
Sep 30 14:47:43 KERNEL(Birmingham-AP01-23366@xx.xx.xx.16): [277928.401164] Enabled radar detection on channel 5640
Sep 30 14:47:43 KERNEL(Birmingham-AP01-23366@xx.xx.xx.16): [277928.401164] dfs_radar_enable: firpwr=0, rssi=0, height=0, prssi=0, inband=0, relpwr=0, relstep=0, maxlen=0
Sep 30 14:47:43 KERNEL(Birmingham-AP01-23366@xx.xx.xx.16): [277928.401195] dfs_radar_enable: duration multiplier is 72
Sep 30 14:47:43 KERNEL(Birmingham-AP02-23369@xx.xx.xx.10): [1510645.594953] dfs_init_radar_filters: dfsdomain=2, numradars=9, numb5radars=0
Sep 30 14:47:43 KERNEL(Birmingham-AP02-23369@xx.xx.xx.10): [1510645.595016] dfs_radar_enable: firpwr=0, rssi=0, height=0, prssi=0, inband=0, relpwr=0, relstep=0, maxlen=0
Sep 30 14:47:43 KERNEL(Birmingham-AP02-23369@xx.xx.xx.10): [1510645.595047] Enabled radar detection on channel 5520
Sep 30 14:47:43 KERNEL(Birmingham-AP02-23369@xx.xx.xx.10): [1510645.595047] dfs_radar_enable: duration multiplier is 72
Sep 30 14:47:43 KERNEL(Birmingham-AP08-23362@xx.xx.xx.15): [1510639.262932] dfs_init_radar_filters: dfsdomain=2, numradars=9, numb5radars=0
Sep 30 14:47:43 KERNEL(Birmingham-AP08-23362@xx.xx.xx.15): [1510639.262995] Enabled radar detection on channel 5660
Sep 30 14:47:43 KERNEL(Birmingham-AP08-23362@xx.xx.xx.15): [1510639.262995] dfs_radar_enable: duration multiplier is 72
Sep 30 14:47:43 KERNEL(Birmingham-AP08-23362@xx.xx.xx.15): [1510639.262995] dfs_radar_enable: firpwr=0, rssi=0, height=0, prssi=0, inband=0, relpwr=0, relstep=0, maxlen=0
Sep 30 14:47:44 KERNEL(Birmingham-AP01-23366@xx.xx.xx.16): [277929.401070] dfs_init_radar_filters: dfsdomain=2, numradars=9, numb5radars=0
Sep 30 14:47:44 KERNEL(Birmingham-AP01-23366@xx.xx.xx.16): [277929.401133] dfs_radar_enable: firpwr=0, rssi=0, height=0, prssi=0, inband=0, relpwr=0, relstep=0, maxlen=0
Sep 30 14:47:44 KERNEL(Birmingham-AP01-23366@xx.xx.xx.16): [277929.401164] Enabled radar detection on channel 5640
Sep 30 14:47:44 KERNEL(Birmingham-AP01-23366@xx.xx.xx.16): [277929.401164] dfs_radar_enable: duration multiplier is 72
Sep 30 14:47:44 KERNEL(Birmingham-AP02-23369@xx.xx.xx.10): [1510646.594922] dfs_init_radar_filters: dfsdomain=2, numradars=9, numb5radars=0
Sep 30 14:47:44 KERNEL(Birmingham-AP02-23369@xx.xx.xx.10): [1510646.594985] Enabled radar detection on channel 5520
Sep 30 14:47:44 KERNEL(Birmingham-AP02-23369@xx.xx.xx.10): [1510646.594985] dfs_radar_enable: duration multiplier is 72
Sep 30 14:47:44 KERNEL(Birmingham-AP02-23369@xx.xx.xx.10): [1510646.594985] dfs_radar_enable: firpwr=0, rssi=0, height=0, prssi=0, inband=0, relpwr=0, relstep=0, maxlen=0
Sep 30 14:47:44 KERNEL(Birmingham-AP08-23362@xx.xx.xx.15): [1510640.262870] dfs_init_radar_filters: dfsdomain=2, numradars=9, numb5radars=0
Sep 30 14:47:44 KERNEL(Birmingham-AP08-23362@xx.xx.xx.15): [1510640.262963] Enabled radar detection on channel 5660
Sep 30 14:47:44 KERNEL(Birmingham-AP08-23362@xx.xx.xx.15): [1510640.262963] dfs_radar_enable: duration multiplier is 72
Sep 30 14:47:44 KERNEL(Birmingham-AP08-23362@xx.xx.xx.15): [1510640.262963] dfs_radar_enable: firpwr=0, rssi=0, height=0, prssi=0, inband=0, relpwr=0, relstep=0, maxlen=0
Sep 30 16:36:16 KERNEL(Birmingham-AP08-23362@xx.xx.xx.15): [1517152.280864] dfs_init_radar_filters: dfsdomain=2, numradars=9, numb5radars=0
Sep 30 16:36:16 KERNEL(Birmingham-AP08-23362@xx.xx.xx.15): [1517152.280958] Enabled radar detection on channel 5660
Sep 30 16:36:16 KERNEL(Birmingham-AP08-23362@xx.xx.xx.15): [1517152.280958] dfs_radar_enable: duration multiplier is 72
Sep 30 16:36:16 KERNEL(Birmingham-AP08-23362@xx.xx.xx.15): [1517152.280958] dfs_radar_enable: firpwr=0, rssi=0, height=0, prssi=0, inband=0, relpwr=0, relstep=0, maxlen=0
Sep 30 16:36:17 KERNEL(Birmingham-AP01-23366@xx.xx.xx.16): [284442.258646] dfs_init_radar_filters: dfsdomain=2, numradars=9, numb5radars=0
Sep 30 16:36:17 KERNEL(Birmingham-AP01-23366@xx.xx.xx.16): [284442.258740] Enabled radar detection on channel 5640
Sep 30 16:36:17 KERNEL(Birmingham-AP01-23366@xx.xx.xx.16): [284442.258740] dfs_radar_enable: duration multiplier is 72
Sep 30 16:36:17 KERNEL(Birmingham-AP01-23366@xx.xx.xx.16): [284442.258740] dfs_radar_enable: firpwr=0, rssi=0, height=0, prssi=0, inband=0, relpwr=0, relstep=0, maxlen=0
Sep 30 16:36:17 KERNEL(Birmingham-AP08-23362@xx.xx.xx.15): [1517153.280864] dfs_init_radar_filters: dfsdomain=2, numradars=9, numb5radars=0
Sep 30 16:36:17 KERNEL(Birmingham-AP08-23362@xx.xx.xx.15): [1517153.280958] Enabled radar detection on channel 5660
Sep 30 16:36:17 KERNEL(Birmingham-AP08-23362@xx.xx.xx.15): [1517153.280958] dfs_radar_enable: duration multiplier is 72
Sep 30 16:36:17 KERNEL(Birmingham-AP08-23362@xx.xx.xx.15): [1517153.280958] dfs_radar_enable: firpwr=0, rssi=0, height=0, prssi=0, inband=0, relpwr=0, relstep=0, maxlen=0
Sep 30 16:36:18 KERNEL(Birmingham-AP01-23366@xx.xx.xx.16): [284443.258615] dfs_init_radar_filters: dfsdomain=2, numradars=9, numb5radars=0
Sep 30 16:36:18 KERNEL(Birmingham-AP01-23366@xx.xx.xx.16): [284443.258709] Enabled radar detection on channel 5640
Sep 30 16:36:18 KERNEL(Birmingham-AP01-23366@xx.xx.xx.16): [284443.258709] dfs_radar_enable: duration multiplier is 72
Sep 30 16:36:18 KERNEL(Birmingham-AP01-23366@xx.xx.xx.16): [284443.258709] dfs_radar_enable: firpwr=0, rssi=0, height=0, prssi=0, inband=0, relpwr=0, relstep=0, maxlen=0
Sep 30 16:36:20 KERNEL(Birmingham-AP02-23369@xx.xx.xx.10): [1517162.538409] dfs_init_radar_filters: dfsdomain=2, numradars=9, numb5radars=0
Sep 30 16:36:20 KERNEL(Birmingham-AP02-23369@xx.xx.xx.10): [1517162.538471] Enabled radar detection on channel 5520
Sep 30 16:36:20 KERNEL(Birmingham-AP02-23369@xx.xx.xx.10): [1517162.538471] dfs_radar_enable: firpwr=0, rssi=0, height=0, prssi=0, inband=0, relpwr=0, relstep=0, maxlen=0
Sep 30 16:36:20 KERNEL(Birmingham-AP02-23369@xx.xx.xx.10): [1517162.538503] dfs_radar_enable: duration multiplier is 72
Sep 30 16:36:21 KERNEL(Birmingham-AP02-23369@xx.xx.xx.10): [1517163.538409] dfs_init_radar_filters: dfsdomain=2, numradars=9, numb5radars=0
Sep 30 16:36:21 KERNEL(Birmingham-AP02-23369@xx.xx.xx.10): [1517163.538471] dfs_radar_enable: firpwr=0, rssi=0, height=0, prssi=0, inband=0, relpwr=0, relstep=0, maxlen=0
Sep 30 16:36:21 KERNEL(Birmingham-AP02-23369@xx.xx.xx.10): [1517163.538503] Enabled radar detection on channel 5520
Sep 30 16:36:21 KERNEL(Birmingham-AP02-23369@xx.xx.xx.10): [1517163.538503] dfs_radar_enable: duration multiplier is 72
Which ties in with the AP timestamps below for AP02:
2019-09-30 16:35:24 Trying new VRRP master for LMS xx.xx.xx.5. Old VRRP master switch IP is 3.25.199.44
2019-09-30 16:36:10 Trying new VRRP master for LMS xx.xx.xx.5. Old VRRP master switch IP is 3.25.197.180