Do you have Smart Connect enabled by chance? (Advanced>Wireless>Wireless Settings). If so try disabling it and then setting a different SSID name for the 5Ghz band and then check if you can see the...

ccnaxpired wrote Are the encryption settings compatible?... WPA vs WPA2Are the modes compatible?... n/ac mixed vs ac only?Use the lower 5GHz channels, 36 to 48 (try 40MHz and 80MHz wide).I'm learning...