Everything from the videos.

Play-In-Editor runs your server and client inside one program on localhost — shared memory, zero lag, zero packet loss. Code that replicates nothing can still look like it works. This launches a REAL dedicated server and REAL clients as separate processes, over a real socket, with simulated lag. You cannot misconfigure your way back into the lie.

@echo offsetlocal EnableDelayedExpansioncd /d "%~dp0"title Netcade - Dedicated Server + Clientscolor 0BREM ===========================================================================REM  NETCADE MULTIPLAYER TEST LAUNCHERREMREM  Launches a REAL dedicated server and REAL clients as SEPARATE PROGRAMS,REM  over a REAL socket, with SIMULATED LAG.REMREM  WHY THIS EXISTSREM  ---------------REM  Play-In-Editor runs your server and client inside ONE program, so theyREM  share memory. Code that replicates nothing can still look like it works.REM  Localhost also gives you 0ms ping and 0% packet loss, which no human has.REMREM  "Run Under One Process" is an EDITOR preference. This .bat ignores itREM  completely - it starts two separate .exe processes at the OS level. YouREM  cannot accidentally misconfigure your way back into the lie.REMREM  Network emulation works in DEVELOPMENT builds only, never in Shipping.REM  Epic's own test conditions: 500ms round-trip, 10% packet loss.REM ===========================================================================REM ------------------- EDIT THESE -------------------set "UE=C:\Program Files\Epic Games\UE_5.8\Engine\Binaries\Win64\UnrealEditor.exe"set "PROJECT=%~dp0NetcadeYT.uproject"set "MAP=Lvl_ThirdPerson"set "PORT=7777"set "MAXTRIES=120"REM --------------------------------------------------if not exist "%UE%" (  echo.  echo   Can't find Unreal at:  %UE%  echo   Open this .bat in Notepad and fix the UE= line at the top.  echo.  pause & exit /b 1)if not exist "%PROJECT%" (  echo.  echo   Can't find the project:  %PROJECT%  echo   Put this .bat next to your .uproject file.  echo.  pause & exit /b 1)echo.echo   =========================================================echo     NETCADE  -  DEDICATED SERVER + CLIENTSecho   =========================================================REM ---------------- how many clients ----------------echo.set "CLIENTS="set /p "CLIENTS=  How many clients? [1-6, default 2]: "if "%CLIENTS%"=="" set "CLIENTS=2"set /a CLIENTS=CLIENTS+0if %CLIENTS% LSS 1 set "CLIENTS=1"if %CLIENTS% GTR 6 set "CLIENTS=6"REM ---------------- network conditions ----------------echo.echo   Network conditions:echo.echo     1) Perfect      0 ms          - localhost. This is the lie.echo     2) Good        40 ms          - fibre, same countryecho     3) Average    120 ms,  1%%     - a normal playerecho     4) Bad        300 ms,  3%%     - wifi, far awayecho     5) Brutal     500 ms, 10%%     - Epic's own test conditionsecho     6) Customecho.set "NET="set /p "NET=  Choose [3]: "if "%NET%"=="" set "NET=3"REM PktLag is ONE-WAY delay in ms. Applied to BOTH ends, so the round-tripREM ping you actually feel is roughly DOUBLE the number below.set "EMU="if "%NET%"=="1" set "EMU="if "%NET%"=="2" set "EMU=-PktLag=20 -PktLagVariance=5"if "%NET%"=="3" set "EMU=-PktLag=60 -PktLagVariance=15 -PktLoss=1"if "%NET%"=="4" set "EMU=-PktLag=150 -PktLagVariance=40 -PktLoss=3"if "%NET%"=="5" set "EMU=-PktLag=250 -PktLagVariance=50 -PktLoss=10"if "%NET%"=="6" (  echo.  set /p "LAG=  One-way lag in ms [120]: "  set /p "VAR=  Lag variance in ms [30]: "  set /p "LOSS=  Packet loss %% [2]: "  if "!LAG!"==""  set "LAG=120"  if "!VAR!"==""  set "VAR=30"  if "!LOSS!"=="" set "LOSS=2"  set "EMU=-PktLag=!LAG! -PktLagVariance=!VAR! -PktLoss=!LOSS!")echo.echo   ------------------------------------------------echo     Map      : %MAP%echo     Clients  : %CLIENTS%if defined EMU (  echo     Network  : %EMU%  echo                ^(server AND clients - round trip is about 2x the lag^)) else (  echo     Network  : none. Zero lag. This is not a real test.)echo   ------------------------------------------------echo.pauseREM ---------------- dedicated server ----------------echo.echo   [1/2] Dedicated server ...netstat -an | findstr ":%PORT%" >nul 2>&1if not errorlevel 1 (    echo         Already listening on %PORT% - reusing it.    goto clients)echo         Starting headless dedicated server ...start "DEDICATED SERVER" "%UE%" "%PROJECT%" %MAP% -server -port=%PORT% -log %EMU%echo         Waiting for port %PORT% ^(first run compiles shaders - be patient^) ...set /a TRIES=0:waitloopping -n 3 127.0.0.1 >nulnetstat -an | findstr ":%PORT%" >nul 2>&1if not errorlevel 1 goto serverreadyset /a TRIES+=1<nul set /p "=."if !TRIES! GEQ %MAXTRIES% (    echo.    echo         Server never bound the port. Check its log window.    echo.    pause & exit /b 1)goto waitloop:serverreadyecho.echo         Server is listening on %PORT%.REM ---------------- clients ----------------:clientsecho.echo   [2/2] Launching %CLIENTS% client^(s^) ...for /l %%i in (1,1,%CLIENTS%) do (  echo         client #%%i ...  start "CLIENT %%i" "%UE%" "%PROJECT%" 127.0.0.1:%PORT% -game -log -windowed -ResX=1280 -ResY=720 %EMU%  if not %%i==%CLIENTS% ping -n 4 127.0.0.1 >nul)echo.echo   ================================================echo     Running. Server + %CLIENTS% client(s).echo.echo     Change lag LIVE in any client console (~ key):echo        NetEmulation.PktLag 400echo        NetEmulation.PktLoss 15echo        NetEmulation.Offecho   ================================================echo.echo     *** PRESS ANY KEY IN THIS WINDOW TO KILL   ***echo     *** THE SERVER AND EVERY CLIENT AT ONCE.   ***echo.pause >nulREM ---------------- teardown ----------------REM Kills every UnrealEditor process this .bat started (server + all clients),REM but leaves your actual Unreal EDITOR alone -- the editor is UnrealEditor.exeREM too, so we only kill the ones running with -game or -server on the cmdline.echo.echo   Shutting everything down...for /f "skip=1 tokens=1" %%p in ('wmic process where "name='UnrealEditor.exe'" get ProcessId 2^>nul') do (  for /f "delims=" %%c in ('wmic process where "ProcessId=%%p" get CommandLine /value 2^>nul ^| find "="') do (    echo %%c | find /i "-server" >nul && taskkill /F /PID %%p >nul 2>&1    echo %%c | find /i "-game"   >nul && taskkill /F /PID %%p >nul 2>&1  ))echo   Done. Server and clients terminated. Your editor is untouched.timeout /t 2 /nobreak >nulendlocal