Upsmon error Signal 15: exiting

Hello,

I am trying to configure my OpenWRT router as a nut client, so it can be shutdown in case of power failure by my main UPS which is connected to a Raspberry Pi. I installed these packages nut nut-common nut-upsmon nut-upsc, and I modified the /etc/config/nutmonitor file like this:

config upsmon 'upsmon'
       option runas nutmon
       option minsupplies 1
       option shutdowncmd '/usr/sbin/nutshutdown'
       list defaultnotify SYSLOG
       option pollfreq 10
       option pollfreqalert 5
       option hostsync 25
       option deadtime 30
       option rbwarntime 43200
       option nocommwarntime 300
       option finaldelay 5

config slave
       option upsname ups-eaton
       option hostname 192.168.93.233
       option powervalue 1
       option username upsmon_remote
       option password xxx

My problem is that approximately every minute, I get these messages in the syslog:

Sun Mar  7 22:17:41 2021 daemon.err upsmon[14479]:    0.000000  Using power down flag file /var/run/killpower
Sun Mar  7 22:17:41 2021 daemon.err upsmon[14479]:    0.001667  UPS: ups-eaton@192.168.93.233 (slave) (power value 1)
Sun Mar  7 22:17:41 2021 daemon.err upsmon[14479]:    0.006079  debug level is '1'
Sun Mar  7 22:17:41 2021 daemon.err upsmon[14479]:    0.016479  Trying to connect to UPS [ups-eaton@192.168.93.233]
Sun Mar  7 22:17:42 2021 daemon.err upsmon[14479]:    0.023391  Logged into UPS ups-eaton@192.168.93.233
Sun Mar  7 22:18:48 2021 daemon.err upsmon[14479]:   66.986526  Signal 15: exiting
Sun Mar  7 22:18:48 2021 daemon.err upsmon[14479]:   66.987707  upsmon parent: read
Sun Mar  7 22:18:49 2021 daemon.err upsmon[14626]: kill: No such process

I tried searching but I can't find a solution to this problem, does anyone know what could cause this?
Thank you!