I'm in an Airbnb and the access point has the same name for 5ghz and 2.4ghz. Apple doesn't let you manually switch. The only way I've found to switch when one is not working is to toggle the wifi on/off fifty times.
I think there must be some sort of crazy interference going on because I can literally be sitting right next to the router and 5ghz has about 5k of bandwidth available.