There's no problem using the Ultra on a 5 GHz access point. And it's likely you will have less interference using that band. The question will be: is it faster? It certainly has the potential, and I have heard other users say it's faster for them. But for me, I've never gotten any faster speeds than using my Ethernet connection.
However, there's only one reason you'd ever need a higher speed than either the Ethernet connection (tops out at 100 Mbps) or one of the WiFi bands (theoretical speeds of 300 to over 1000 Gbps), and that's if you are streaming uncompressed UHD video from a home server. There's nothing that streams from the Internet that is likely to exceed 20 Mbps. Netflix tops out at 16 Mbps for 4K/HDR, and Amazon and Vudu are about the same.
Dan
Roku Stick (3600), Ultra (4640), Ultra (4670), Ultra (4800), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.
