http://forum.mikrotik.com/viewtopic.php?f=2&t=60002
To be able to roll back to a previous working version and the reason for upgrading was for performance reasons, Mikrotik should list previous versions and not the latest and then 4.17 as Legacy, thanks to helpful forum user I was able to download a previous version but as mentioned they should be in the Mikrotik Archive.if you don't use v5.14 (or whatever is the latest), you will not get any support and even on the forum you won't get any real assistance. We release versions for a good reason.