Hi,
i have bundle of MTs in my network, all od them are licenced 2.9.50 lvl4. I indent to upgrade it to 3.x, what u suggest to me ? To do it or not, if not why, if yes why ? 
Best regards,
There is this wonderful button at the top of this page called “search” - USE IT.
I suggest you to download the latest NPK file for your system type, upload it with FTP to your router, then reboot.
Latest for 2.x or 3.x ?
3.0
Thanks. May God bless u