eap_peer_config::fragment_size field

fragment_size - Maximum EAP fragment size in bytes (default 1398) This value limits the fragment size for EAP methods that support fragmentation (e.g., EAP-TLS and EAP-PEAP). This value should be set small enough to make the EAP messages fit in MTU of the network interface used for EAPOL. The default value is suitable for most cases.