during boot-up stackmembers stay long in state "VLAN sync" when learning is disabled on some VLANs
When rebooting a stack with many VLANs (400+) and some of them have learning disabled, the stack-members stay very long in state "vlan sync"
learning disabled on some VLANs
With many VLANs configured the VLAN syncing between stack-members during boot-up already takes some time, however when learning is also disabled on some VLANs and is enabled on others, this might take even longer as software-learning is then enabled on the specific ports and learning is then not done in hardware anymore.
Either leave learning enabled on the ports, or upgrade to a version that includes xos0072870 (220.127.116.11-patch1-4 or higher for 16.2 or 22.7)