Scary warning: 40 Mhz and 20 Mhz coexistence?

Hello

 

So I use my Mac's Wireless Diagnostics WiFi scanner tool to find the best 2.4GHz and 5GHz WiFi channels to use then I enter my two selected channels into the Wireless Settings page of the Netgear Orbi web console. When I apply the changes, I get the following scary message:

"Per Wi-Fi Alliance guidelines for 40 Mhz and 20 Mhz coexistence, even if you select 'Up to 400Mbps' mode, your product’s service rate might drop to 20 Mhz. This typically corresponds to 192 Mbps performance."

 

Thanks