EX7700 extender recommends I change my router's 5 ghz channel. Why?

[r-a-m]

Can someone give me a brief overview as to why my EX7700 might recommend that I change the channel of my ASUS router?

Extender's webpage says: "To get the best WiFi performance, we recommend that you change the 5 GHz WiFi channel on your

router to a channel between 100 and 165."

Router (an ASUS RT-AC66U) currently provides 5ghz channel 48.

Extender currently provides 5ghz channel 149.

Performance is good, so I'm reluctant to make the change without some motivation.

Thanks in advance for any insight.

[plemans]

The 100-165 channels are DFS channels. Meaning they tend to have less interfence. So unless you live by an  airport/military base, they tend to not be used. So the performance on them can be more stable. So for the extender, having its dedicated backhaul link to the router be on the most stable channel, makes sense.