MTU (Maximum transmission unit ) defines the largest size of packets (layer 3) that an interface can transmit without the need to fragment.
The MTU of an Ethernet connection by default = 1500 bytes. If a system sends packets over an Ethernet network that are larger than 1500 bytes, the data will be fragmented into smaller packets.
To calculate: MTU = MSS + 40 where:
MSS (Maximum segment size) is a parameter of the options field of the TCP header that specifies the largest amount of data, specified in bytes, that a computer or communications device can receive in a single TCP segment and 40 = IP ( 20 bytes) + TCP ( 20 bytes).
If you set the MTU of the interface to 1492, you should see the MSS to 1452.
The TCP/IP doesn't limit the size of the data of the segment; Ethernet defines the maximum size of the dates before the encapsulation; IP defines the maximum size of the dates after the encapsulation;
At layer 2 OSI the minimum size of a frame (Ethernet) could be 64 bytes and the maximum 1518 bytes.
So I think you should analyse the problem in terms of protocols, not devices.