Lines 1 - 10 are boot messages. It is difficult to tell when they actually happen because the router doesn't remember the date/time. It is LIKELY that is is around the 1400 time because the next item is at 14:15. It is interesting that one device in lines 12 - 14 has to ask for an IP address three times in less than an hour. That is odd, but not specific of any thing.
IF you didn't power cycle the router, then it might be spontaneously rebooting. It would be unusual for there to be so little in the log unless it had been rebooted recently.
i have to reboot 3-4 times/day because, if i do not do that i can't get access to the internet via wifi, this issue persists for years already.
also if there is only one device connected to the wifi, this issue doesn't happen, but if there is more than one device connected, i have to restart in a couple of hours or minutes.
it usually goes like this, i just get disconnected from the internet via wifi and phone indicator says, wifi/connected no internet. and if i try to reconnect it takes a lot of time and saying obtaining IP address but still goes to no internet, the same happens if i restart the phone or use "forget network" option.