It's realy easy to configure your Mordhau Server Map Rotation with Servernetic. Simply follow the steps below:
1.) Open the Configuration Tool.
Configuration Files > Game.ini > [ Text Editor ]
2.) Configure your Map Rotation
You can change the default map rotation by modifying the lines below [/Script/Mordhau.MordhauGameMode].
FL = Frontline
BR = Battle Royale
HRD = Horde
SKM = Skirmish
FFA = FFA/Deathmatch
TDM = Team Deathmatch
For example, if you want a Skirmish mode only server, your file should look like this:
[/Script/Mordhau.MordhauGameMode]
MapRotation=SKM_Contraband
MapRotation=SKM_ThePit
MapRotation=SKM_Grad
MapRotation=SKM_Camp
*NOTE: By default, the server always loads SKM_Contraband as the first map in the rotation. To change this, read below.
3.) Configure the Servers Default Map
Commandline Manager > Custom Commandlines > New
Description
Choose any description you like. For example: TDM Contraband
Default Map
Choose the Default Map. For example: TDM_Contraband (Make sure to check the checkbox!)
Source: Mordhau Forums