Tasmota MAX_DOMOTICZ_IDX erhöhen

Your change will break future tasmota upgrades but then that's what you've choosen.

First, while changing MAX_DOMOTICZ_IDX from 4 to anything else you must have read the header above it saying:

/*********************************************************************************************\ * Constants
\*********************************************************************************************/

// Changes to the following MAX_ defines will impact settings layout
const uint8_t MAX_SWITCHES = 8;             // Max number of switches
const uint8_t MAX_RELAYS = 8;               // Max number of relays
const uint8_t MAX_INTERLOCKS = 4;           // Max number of interlock groups (MAX_RELAYS / 2)
const uint8_t MAX_LEDS = 4;                 // Max number of leds
const uint8_t MAX_KEYS = 4;                 // Max number of keys or buttons
const uint8_t MAX_PWMS = 5;                 // Max number of PWM channels
const uint8_t MAX_COUNTERS = 4;             // Max number of counter sensors
const uint8_t MAX_TIMERS = 16;              // Max number of Timers
const uint8_t MAX_PULSETIMERS = 8;          // Max number of supported pulse timers
const uint8_t MAX_DOMOTICZ_IDX = 4;         // Max number of Domoticz device, key and switch indices

As the settings layout is a fixed area of exactly 4k memory any increase of the above values will overflow the area with unstable system result.

In your case if you increase the value you will need to go over the settings area and find the impact of the change. You'll notice the define MAX_DOMOTICZ_IDX pops up three times in settings.h. Any increase needs extra storage space you will need to calculate how many bytes are needed for a single increment. Then find a location within the 4k settings to decrement the same amount to keep the total exactly 4k (4096 bytes). Look for variable free_f43[117] and decrement the index with your calculated number of bytes. I leave the calculation to you to get some feeling with the procedure. Oh and keep in mind to have the uint32_t variables exactly on a 4-byte binary so as the define also increases a uint16_t I would recommend to increase by steps of 2. Again, dive in C as a real ESPCustomizer and learn a lot.

Good luck and remember any default Tasmota will binary will break your system as the settings have been moved from their default location.