@Kevin_Z It is a well known use case to need different SSID for 5GHz & 2.5GHz . See https://www.tech21century.com/separate-ssid-for-2-4-and-5-ghz-on-orbi/ (albeit the article is about an Orbi). It is...

I've just set up my Deco P9. It seems I can't set up a different SSID for 2.5GHz vs 5GHz Wi-Fi. Is this really true?