How to set up the AS923-3 frequency plan?

Below is the AS923-3 frequency plan. 917.3 and 917.5 are the two default channels set up through TTN. In addition to this,other channels must be set up in the network server and LoRaWAN gateway.
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We did try TTN to set up the channels based on AS923-3 frequency plan but ended up in failure beacuse couldn’t find the UI for frequency settings.