@Levon 

My answer might not be of much help, but my A20 has similar LOG entries:

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2021-02-23 14:06:43 led-controller[1424]: <6> 288051 Start to run USB1
2021-02-23 07:00:00 led-controller[1424]: <6> 288051 Start to run NIGHT
2021-02-23 06:23:55 led-controller[1424]: <6> 288051 Start to run WAN1_ON
2021-02-23 06:23:55 led-controller[1424]: <6> 288051 Start to run WAN0_OFF
2021-02-23 06:23:55 led-controller[1424]: <6> 288051 Start to run LAN_ON
2021-02-22 20:00:00 led-controller[1424]: <6> 288051 Start to run NIGHT
2021-02-22 19:55:16 led-controller[1424]: <6> 288051 Start to run WAN1_ON
2021-02-22 19:55:16 led-controller[1424]: <6> 288051 Start to run WAN0_OFF
2021-02-22 19:55:16 led-controller[1424]: <6> 288051 Start to run LAN_OFF
2021-02-22 07:00:00 led-controller[1424]: <6> 288051 Start to run NIGHT
2021-02-22 06:08:59 led-controller[1424]: <6> 288051 Start to run WAN1_ON
2021-02-22 06:08:59 led-controller[1424]: <6> 288051 Start to run WAN0_OFF
2021-02-22 06:08:59 led-controller[1424]: <6> 288051 Start to run LAN_ON
2021-02-22 06:08:51 led-controller[1424]: <6> 288051 Start to run WAN1_ON
2021-02-22 06:08:51 led-controller[1424]: <6> 288051 Start to run WAN0_OFF
2021-02-22 06:08:51 led-controller[1424]: <6> 288051 Start to run LAN_OFF
2021-02-22 04:44:43 led-controller[1424]: <6> 288051 Start to run WAN1_ON
2021-02-22 04:44:43 led-controller[1424]: <6> 288051 Start to run WAN0_OFF
2021-02-22 04:44:43 led-controller[1424]: <6> 288051 Start to run LAN_ON
2021-02-21 20:00:00 led-controller[1424]: <6> 288051 Start to run NIGHT
2021-02-21 19:48:54 led-controller[1424]: <6> 288051 Start to run WAN1_ON
2021-02-21 19:48:54 led-controller[1424]: <6> 288051 Start to run WAN0_OFF
2021-02-21 19:48:54 led-controller[1424]: <6> 288051 Start to run LAN_OFF
2021-02-21 07:00:00 led-controller[1424]: <6> 288051 Start to run NIGHT
2021-02-21 06:17:50 led-controller[1424]: <6> 288051 Start to run WAN1_ON
2021-02-21 06:17:50 led-controller[1424]: <6> 288051 Start to run WAN0_OFF
2021-02-21 06:17:50 led-controller[1424]: <6> 288051 Start to run LAN_ON
2021-02-20 20:00:00 led-controller[1424]: <6> 288051 Start to run NIGHT
2021-02-20 19:44:11 led-controller[1424]: <6> 288051 Start to run WAN1_ON
2021-02-20 19:44:11 led-controller[1424]: <6> 288051 Start to run WAN0_OFF
2021-02-20 19:44:11 led-controller[1424]: <6> 288051 Start to run LAN_OFF
2021-02-20 09:06:29 led-controller[1424]: <6> 288051 Start to run WAN1_ON
2021-02-20 09:06:29 led-controller[1424]: <6> 288051 Start to run WAN0_OFF
2021-02-20 09:06:29 led-controller[1424]: <6> 288051 Start to run LAN_ON
2021-02-20 07:00:00 led-controller[1424]: <6> 288051 Start to run NIGHT
2021-02-19 20:00:00 led-controller[1424]: <6> 288051 Start to run NIGHT
2021-02-19 19:57:30 led-controller[1424]: <6> 288051 Start to run WAN1_ON
2021-02-19 19:57:30 led-controller[1424]: <6> 288051 Start to run WAN0_OFF
2021-02-19 19:57:30 led-controller[1424]: <6> 288051 Start to run LAN_OFF

=======================

I do have NIGHT mode for LED's enabled:

Doesn't explain all the changes though by time. Still, I've not seen any wireless drops on our PC's from our A20?

I find the LOGGING not to be of much value and a lot of useful data one could get in a log just isn't there compared to other router's I've used.

I also think, but I'm not sure, the ones above I've made BOLD is due to the specific PC being turned on? Not sure because that PC can run both wired and wireless. Usually wireless, but the Ethernet cable is connected all the time between the 2. You have a similar situation, a wired PC turning on/off even if the wired connection is not used?

Like I said, LOGGING is lacking. Using the Log Filter Type pulldown I see a lot of possible features, and I'm set to ALL... NEVER have I seen most of them. I keep my logs too, sent to me by e-mail every day, and unless the router is powered off, the log will be for many days I guess until the space in RAM for it fills up and then it drops off the oldest entry, so I can see many days on each log... never saw some of those entries?

@IrvSp Thanks for taking the time to post (sorry about the delay in my response). Like you I also get my logs mailed regularly. I guess I will have to dig in some more and see if the timings correspond to my PC being on or (my PC has a hardwired connection and usually stays on). I have a laptop and various other wifi devices connected too.