The example network interface for ATSAME5x does not correctly detect ICMP packets. The codes checks the protocol byte but fails to also check the Ethernet frame type. This causes it to get false-positive matches for frames which happen to have an 0x01 byte at a certain offset.
The same bug exists in two places in the code: xATSAM5x_NetworkInterfaceOutput() and prvEMACDeferredInterruptHandlerTask(). I will be submitting a pull-request which fixes it.