How to toggle AP to 2.4 ghz

Have soho with firmware 6.3.1
It appears that the wifi Channels are 5ghz and I have a device that needs 2.4ghz

How to change to 2.4. AND can I have both at the same time? How?

Please go AP > Settings > Wi-Fi AP Settings > Protocol = 802.11ng.

Surf Soho Hw1 and 2 support single radio only. Hence, it supports 2.4GHz or 5GHz at a time. Latest launched Soho MK3 support simultaneous Dual Band.