URGENT - Upgrade RouterOS

Dear All,

i would like to ask you if i can upgrade my RouterOS from 5.6 to 5.22 or 6.0

i’ve RB751U-2HnD (MIPSBE) with License 4

do i’ll face any problem if i upgrade it, like losing certificate or the Router will not working anymore ???

Thank You

no. simply upload this file, and reboot the device. it will be fine:
http://download2.mikrotik.com/routeros/5.22/routeros-mipsbe-5.22.npk