Re: LAG and (R/M)STP settings on PC 6224 and PC 5234 switches
I believe his config is invalid. He uses spanning-tree portfast and spanning-tree root-protection on all ports together with spanning-tree bpdu-protection.
Spanning-tree portfast is for end-station ports, it must not be used for links between switches. The bpdu-protection is supposed to disable such port, if it ever sees a STP BPDU. And the root-protection configured on all switches will prevent any of them from becoming STP root.