Restrictions for Per-Port MTU
Per-Port MTU cannot be configured on the management port.
Per-Port MTU cannot be configured on SVL links.
On the C9500-24Y4C, C9500-48Y4C, C9500-32QC, and C9500-32C models of Catalyst 9500 series switch, members of a port channel cannot be configured with Per-Port MTU, they derive their MTU from the port-channel MTU configuration.
On C9500-12Q, C9500-24Q, C9500-40X, and C9500-16X models of Catalyst 9500 series switch, you can configure per-port MTU on the port-channel members, but cannot configure per-port MTU on a port-channel interface.
Per-Port MTU is not supported on sub interfaces and port-channel sub interfaces.