mira125 a nemáš tam něco se starou verzí ? mk měnil chování rstp a durazně nedoporučoval souběžný provoz verzí
RouterOS v6.38 contains STP/RSTP changes which makes bridges compatible with IEEE 802.1Q-2014 by sending and processing BPDU packets without VLAN tag.
To avoid STP/RSTP compatibility issues with older RouterOS versions, upgrade RouterOS to v6.38 on all routers in Layer2 networks with VLAN and STP/RSTP configurations.