You need change file "server.cfg" on your dedicated server.

Example:
----------------------------------------------------------------------------
class Missions
{
class Mission01
{
template = "ultimate_warfare_rubber_edition_stratis.stratis";
difficulty = "veteran";
class Params
{
//RHS Preset
gameplayMainMod = 2;
townsOccupationFactionEast = 6;
townsOccupationFactionWest = 7;
townsResistanceFaction = 2;

baseAICommander = 1;
aiTeams = 1;
};
};
};
----------------------------------------------------------------------------
Template list:

Vanilla:
ultimate_warfare_rubber_edition_altis.altis
ultimate_warfare_rubber_edition_malden.malden
ultimate_warfare_rubber_edition_stratis.stratis
ultimate_warfare_rubber_edition_tanoa.tanoa

CUP:
ultimate_warfare_rubber_edition_abel.abel
ultimate_warfare_rubber_edition_cain.cain
ultimate_warfare_rubber_edition_chernarus.chernarus
ultimate_warfare_rubber_edition_chernarus_s.chernarus_summer
ultimate_warfare_rubber_edition_chernarus_w.chernarus_winter
ultimate_warfare_rubber_edition_eden.eden
ultimate_warfare_rubber_edition_noe.noe
ultimate_warfare_rubber_edition_sara.sara
ultimate_warfare_rubber_edition_sara_u.sara_dbe1
ultimate_warfare_rubber_edition_takistan.takistan
ultimate_warfare_rubber_edition_zargabad.zargabad

IFA3:
ultimate_warfare_rubber_edition_ardennes_1940.swu_ardennes_1940
ultimate_warfare_rubber_edition_ardennes_1944_w.swu_ardennes_1944_winter
ultimate_warfare_rubber_edition_baranow.baranow
ultimate_warfare_rubber_edition_baranow_w.baranowwinter
ultimate_warfare_rubber_edition_panovo.panovo
ultimate_warfare_rubber_edition_panovo_w.panovowinter
ultimate_warfare_rubber_edition_staszow.staszow
ultimate_warfare_rubber_edition_staszow_w.staszowwinter

Vietnam:
ultimate_warfare_rubber_edition_cao_bang.us101_cao_bang
ultimate_warfare_rubber_edition_dakrong.dakrong
ultimate_warfare_rubber_edition_rockwall.rockwall
ultimate_warfare_rubber_edition_rungsat.rungsat

Other maps:
ultimate_warfare_rubber_edition_chernarusredux.chernarusredux
ultimate_warfare_rubber_edition_isla_duala.isladuala3
ultimate_warfare_rubber_edition_fallujah.fallujah
ultimate_warfare_rubber_edition_kunduz.kunduz