assuming it was actually in a file somewhere, lets say your ip is 188.8.131.52. you may be able to find it using this command:
grep -r 184.108.40.206 /etc
this will show you each file under the /etc hierarchy that has the string 220.127.116.11 in it. if you really get desperate, maybe sudo grep -r 18.104.22.168 / (the entire filesystem)
OMV uses systemd-networkd and removes dhcpcd on installation.
This should be used to configure the network including setting IP addresses and (from what I remember) has methods to facilitate this.
If you install another network manager the results will be unpredictable.