I solved my need.
I get the bytes from the EEPROM as well.
#define MY_IP_ADDRESS_B0 EEPROM.read(xxxx)
#define MY_IP_ADDRESS_B3 EEPROM.read(yyyy)
Then I define the address of the gateway like this:
#define MY_IP_ADDRESS ((uint32_t)(MY_IP_ADDRESS_B3) << 24) | ((uint32_t)(MY_IP_ADDRESS_B2) << 16) | ((uint32_t)(MY_IP_ADDRESS_B1) << | (uint32_t)(MY_IP_ADDRESS_B0)
This applies to the other addresses required for the operation of an MQTT gateway.
Hopefully this sharing is useful.