RB 951.
RB951 Ui/G is using MISPBE package !
So, this is latest version for MISPBE based routers:
http://download2.mikrotik.com/routeros/ ... e-6.27.npk
TO gel older packages from ROS, simply change the number in link, for ex for version 6.20 change these paths:
http://download2.mikrotik.com/routeros/6.20/routeros-mipsbe-
6.20.npk
I hope so, that now is more clear how to downgrade the version of ROS. So remember, dont download .zip archive with all packages. Downnoad the wanted .npk file, upload into your MT and restart. Your MT will be downgraded.