Simple batch script that test your internet connection. It tells the number and time of disconnections. Also creates a log file in the c:/ drive with all the events.

cst.bat

@Echo off
title Connection Stability Test / Dascr32
cls

set /A disconnections=1

echo Start time:
time/t

echo ============================================ >> c:\cstb-log.txt
echo Connection Stability Test by Dascr32 Ver 1.2 >> c:\cstb-log.txt
echo. >> c:\cstb-log.txt
echo Start time: >> c:\cstb-log.txt

:: Write time and date to log file
time/t >> c:\cstb-log.txt
date/t >> c:\cstb-log.txt
echo. >> c:\cstb-log.txt

:pingServer
    ping google.com

    if errorlevel 1 (

        echo.
        echo ------------ No Connection ------------
        time/t
        echo.
        set /A disconnections+=1
        echo No. of disconnections: %disconnections%

        :: Write to log file
        echo Status: Disconnected >> c:\cstb-log.txt
        time/t >> c:\cstb-log.txt
        date/t >> c:\cstb-log.txt
        echo No. of disconnections: %disconnections%  >> c:\cstb-log.txt
        echo. >> c:\cstb-log.txt
        
        goto isStillDown
        
    ) else (

        echo.
        echo ------------ Connected ------------
        time/t
    )
    
    :: Loop the test
    goto pingServer

:isStillDown
    ping google.com

    if errorlevel 1 (

        echo ------------ No Connection ------------
        time/t
        
        goto isStillDown

    ) else (

        echo.
        echo ------------ Back online ------------
        time/t

        :: Write to log file
        echo Status: Back online >> c:\cstb-log.txt
        time/t >> c:\cstb-log.txt
        date/t >> c:\cstb-log.txt
        echo. >> c:\cstb-log.txt
        
        goto pingServer
    )