Where is the modbus register map for Unipi 1.1 ?
This is seriously the worst documented thing I have ever worked with.
you are looking for something which doesn't exist. The ModbusTCP service is not available for the Unipi 1.1 since the architecture is very different from the Unipi Neuron and Axon.
You can access to the IOs via methods described in the technical documentation - directly accessing the GPIOs and communicating with the I2C ICs.
Or you can use Evok API (https://github.com/UniPiTechnology/evok), which will make the IOs available via different web-based APIs.
You take any cheap 20$ China Raspberry hat and there is a 2-Page manual (in bad english) that gets you up toggling your inputs and outputs in like 20 minutes.
I have now been digging for at least a solid 5 to 8 hours in the unorganized pile of stuff available here. Best I have found out now is Unipi 1.1 is outdated and abondoned. Existing docs do not mention all the things that are unimplemented.
I will now just throw away the board and not sink any more time in it.