MATTER_MESSAGE_OVERHEAD: number

Message size overhead of a Matter message: 26 (Matter Message Header) + 12 (Matter Payload Header) taken from https://github.com/project-chip/connectedhomeip/blob/2d97cda23024e72f36216900ca667bf1a0d9499f/src/system/SystemConfig.h#L327 16 byte MIC is then also needed to be excluded from the max payload size Secure Extensions and Message Extensions need to be handled by exchange additionally!