можно тогда и покороче:
Код:

@echo off
setlocal enabledelayedexpansion
set "s=Основной шлюз"
set "na1=openvpn"& set "na2=ethernet"
for %%A in ("%na1%" "%na2%") do (
set /a n+=1& set "shl!n!="
for /f "delims=[]" %%a in ('ipconfig /all^|find /n "%%~A"') do set "ns=%%a"
for /f "tokens=2 delims=:" %%a in ('ipconfig /all^|more +!ns!^|find "%s%"') do if not defined shl!n! set "shl!n!=%%a"
)
echo %shl1: =% %shl2: =%
pause>nul