Good hardware, bad bad bad software
I bought a Kyocera Ecosys M5521cdw in the hope that this will be an economic solution to our household printing needs, after disappointments with larger printer vendors. Sure enough, the printing was OK, toner prices reasonable. There was one memory corruption problem with which I got help from support.
Then, after some time (and printer no longer in support) the printer stopped responding to remote LAN print requests. I am network engineer for 25 years, so I know a bit about protocols and how to install stuff to solve things DIY. But this one is also one of those things that is made just not to work no matter what. Firmware cannot be reset to factory default. USB stick firmware reinstall won't work. NOWHERE in menu to do a factory reset. The printer is pingable, but it won't do anything remotely, so we're confined to using it by USB stick PDF prints and that's it.
Kyocera is now added to my terrible disappointment lists.