HP V1910 Switch Series User Manual page 213

 If the device is not enabled with BPDU guard, when a boundary port receives a BPDU from another
port, it transits into a non-boundary port. To restore its port role as a boundary port, you need to
restart the port.
Configure ports that are directly connected to terminals as boundary ports and enable BPDU guard

for them. These ports can rapidly transit to the forwarding state, and the network security can be
ensured.
199