WiFi limited compatibility

New Iphone and a pretty good router. Setup the phone and get “limited compatibility” under WiFi. This is because my router supports 5 and 6ghz bands. According to Apple this message of “limited compatibility” is because the SSIDs are different. They then go on to say to give them the same name. What router allows that? Am I just dense? So I tried to give my 5 and 6 bands the same names and as predicted, it won’t allow it. What am I not understanding?