wAP ac - 5Ghz-80Mhz Band A Middle 5260Mhz Ceee

Hi,

I recently bought wAP ac access point and have problem with configure 5Ghz band.
So in short for below settings all work correctly:
Frequency: 5180
Control Channel: 20Mhz
Band: 5ghz-a/n/ac
Extension C: Ceee

I wanted to change frequency channel to middle band A: So:
Frequency: 5260
Control Channel: 20Mhz
Band: 5ghz-a/n/ac
Extension C: Ceee

And I don’t have any signal from device. It’s appear for a moment but despite that I’m not able to connect to. Is it something related with DFS ?

Thanks,
Mariusz.