@echo off
cls

rem https://www.securelink.be/windows-proxy-settings-explained/
reg add "HKLM\Software\Microsoft\Windows\CurrentVersion\Internet Settings" /v AutoDetect /t REG_DWORD /d 00000000 /f
reg add "HKLM\Software\Microsoft\Windows\CurrentVersion\Internet Settings" /v ProxyServer /t REG_SZ /d "proxy.beemoon.fr:3128" /f
reg add "HKLM\Software\Microsoft\Windows\CurrentVersion\Internet Settings" /v ProxyEnable /t REG_DWORD /d 00000001 /f
reg add "HKLM\Software\Microsoft\Windows\CurrentVersion\Internet Settings" /v ProxySettingsPerUser /t REG_DWORD /d 00000000 /f

reg add "HKLM\Software\Wow6432Node\Microsoft\Windows\CurrentVersion\Internet Settings" /v AutoDetect /t REG_DWORD /d 00000000 /f
reg add "HKLM\Software\Wow6432Node\Microsoft\Windows\CurrentVersion\Internet Settings" /v ProxyServer /t REG_SZ /d "proxy.beemoon.fr:3128" /f
reg add "HKLM\Software\Wow6432Node\Microsoft\Windows\CurrentVersion\Internet Settings" /v ProxyEnable /t REG_DWORD /d 00000001 /f
reg add "HKLM\Software\Wow6432Node\Windows\CurrentVersion\Internet Settings" /v ProxySettingsPerUser /t REG_DWORD /d 00000000 /f

Ave netsh (ne marche pas pour moi)

netsh winhttp set proxy proxy.beemoon.fr:3128

netsh winhttp reset proxy