At the latest firmware (since 858 and Merlin's 57 - they both works well) - I trys a 1354, 2345, 3341, 3941, and the latest Merlin (58, 59, 62) - I can't connect to router at 5ghz channel (with various option).
Test with my Sony Z3 compact, Xbox One - no 5ghz SSID available (or after phone...