@Glitch, the mwan3 is a stock OpenWrt package, which handles multiple Wan connections (redundancy, load balancing, etc.). It checks periodically if the Wan connection is up by pinging some outside services: Google and OpenDNS in my tests. I can see 4 pings every 5 seconds on my network. These pings exist even if you don’t have multiple Wan connections.
I just removed the packages luci-app-mwan3 (which gives the Network => Load balancing page in LuCI web interface) and mwan3 (which contains the /usr/sbin/mwan3track executable). Then you can remove also the /etc/config/mwan3 config file.
From the command line:
opkg remove luci-app-mwan3 mwan3
rm /etc/config/mwan3