Dear sir,

I bought a new Mikrotik RB450G these days. The original software version is 6.19. I want to use the last version of 5.x.
After downgrade to 5.26 and reboot, I found the software ID was changed and the license level was reset to 0. ???
If I upgrade the same RB450G back to 6.19, the license level 5 is back. I tried many times and got the same result.
Is the problem is a hardware issue? Can anyone help? I really need ROS 5.26.

It is not recommended to downgrade below the version the device was shipped with as mikrotik does undocumented changes in the hardware with the same type but does not maintain the revisions so it normally happens that contemporary hw doesn't run well older sw. This was told by mikrotik many times and they will not provide any way how to make old sw running on new hw.