Hi,

I would like to downgrade a RB750 to V3.30.

Unfortunately, during the V3 to V4 upgrade a xxxx-yyy.key file was not generated.

I have checked other RB4XX systems, and they all have the xxx-yyy.key for V3 in the "files".

Is there any way to downgrade the RB750 to V3.30 and get the V3 key back?

Thanks in advance,

By the way:

I dowgraded to V3.30 and apparently the RB750 is happy with the V4 key...

your old key is in your mikrotik.com account, but don't use it. v3 works fine with new keys (after v3.25)

I noticed a .key file in many of my routers now. Is this file necessary or can it be deleted?

it's just a backup of old-format keys. if all is working fine, just delete it. anyway, it should be in your mikrotik.com account