Single Channel Gateway

I’ve got two gateways. LG01 and OLG01 and want to connect 2 ESP32 (Heltec LoRa 32v2)
One is already working, but the second one doesnt connect to one of the Gateways.
I heard i have to limit the transmissions to one channel and one spreading factor.
How can i modify my code?
I use the code for the paxcounter from cyberman54 (Github) in Visual Studio Code with the Platformio Extension.