RouterOS License lost on downgrade

Hardware MikroTik hardware general
1

Hello,

We have recieved a lot of routerboards 951Ui-2HnD and RB2011UiAS-2HnD
they have ROS 6.18, and then I downgrade to any 6.x License become Level 0 and software ID after any reboot is different.
If I import earlier exported license - ROS say it’s invalid
I tried netinstall to 6.x versions - but no success

Then i upgrade to 6.18, all works like a charm

P.S. Customers will buy routerboards only if routers operate at ROS 6.5, since their devices works only on this version.

Thanks.

2

Official statement of mikrotik was repeated many times here: don’t downgrade below the version that was device shipped with as it may not work.