Radio Lora of 900 or 400 mhz, for RTK? Configuration.?

Thank you for giving me the opportunity to use this forum.
I will soon buy an Alpha + to replace my old Geoexplorer, as there is no radio module offered, I am looking at the offers that exist, but I find two configurations
400 and 900 mhz, one has a range of 3 km and the other 8 km, the immediate question is: which is better for the Alpha?
Also the inputs of both modules is RS 232, how can I configure the connection cable? The communication software with the GPS module?

Please, i need more information for this also.

Hello, Thanks for your answers, it is clear to me where to start, regarding the wiring with the GPS module, but I still have the question of whether to use a 433 or 900 mhz module, according to the models indicated below,

  1. Ebyte E32-DTU (433L30) LoRa SX1278 RS232 RS485 433MHz 30dBm 1W
  2. LoRa SX1276 RS485 RS232 20dBm, E32-DTU-915L20 transmitter and receiver, uhf DTU 915MHz, 915MHz RF module

Both are very cheap, no more than 20 dollars, I am not an expert on the subject so I do not know which is the best to use

Vou fazer a conexão via rádio do S100 indicada no blog, alguém podia me dizer qual software devo usar para trabalhar com o rádio e como posso fazer essa configuração?

You can read this:

Support for LoRa and LoRa modelm for RTK Base and Receiver