So we were running a virtual machine on the cloud, that was our RDSH, Win 2012, with 15 2012 CALs. The worst of the worst happened, and let's just say, we lost it completely (accept for our backups of the data, which is all we needed). However, we did need a new server, and desired (due to cost savings), to purchase an in-house server, instead of resuming our cloud use. Unfortunately, the only pre-built servers (as we needed it ASAP), was a 2016 machine, so we bought it, and got everything working again in half a day, not too bad....
Well, after seeing the annoying "120 days, 90 days, now 75 days, of unlimited licenses" warning, I decided it was time to dig up my old CALs (from only 2 year ago, bought summer of 2016). I installed all the old 2012 CALs just fine... but now I learn that 2012 CALs won't allow users to connect to a 2016 RDSH... okay?? So how do I upgrade these, or is this just some... you're s.o.l., too bad, Microsoft likes licensing fees, and throw those 2012 CALs in the garbage....? And pray we don't have server troubles again, and never upgrade your server version again?