Can I use 433 MHz antenna for 868 MHz (only for test)?

I have a RAK7244 developer gateway with 433 MHz antenna. I have changed the gateway configuration to 868 MHz. Now I can’t see any gateway traffic on the Things Network console.

Is this issue related with the antenna or the LoRa baseband chip?

Nodes used for testing : I have 2 door sensor nodes operating on 868MHz.

The frequency cannot be changed without buying a different LoRaWAN concentrator card. Inputting the wrong frequency in the software will not make it work on an entirely different band.