As an FYI, if that device does not have a 5 GHz band capable WiFi network adapter, it won't see that band at all, only the 2.4 GHz band.
In addition, it may not be able to see either band due to the fact that the two WiFi bands have recently been combined into one with the Comcast gateway devices. Some older devices get confused and don't know how to see / talk to combined bands.
If you are not using any Xfi Pods, you can try separating the 2.4 and the 5.0 bands and give them two different broadcast names / SSID's;
My wireless card is an Intel Duel Band Wireless AC-7260. I can pick up both bands everywhere but in this house. I can see all my neighbors wireless as well. I can also see my wireless on all my other devices.