For Milesight LoRaWAN Controller, the quantity of every Modbus channel is fixed as 1 and not support to change.
Please try below solutions if you need to read Modbus data when quantity is more than 1:
1. If every data can be divided, you can set more Modbus channels to get all data you need.
2. Refer to How to use Modbus RS485 Bridge LoRaWAN Feature to send original Modbus RTU command from server to communicate with RS485 devices. You can set the quantity as any value via original Modbus RTU command.