5Ghz is tend to be more faster at most times, but as the Wi-Fi is is technically such an unpredictable in general (depending on many various environmental circumstances), there's no fix point to give a perfect advise. Switching the HiMedia to the 5GHz band SSID (you should may set first a differential SSID in the router, to independently recognize it) may end better results. There's -maybe- also an alternate option to change the band "channels" in your router, to a less occupied one (by your surroundings Wi-Fi-s), that may could also benefit on the 2.4GHz. For that see your routers manual.
And as the best tip: simply use cables. CAt5e or Cat6 UTP for a more predictable and stable bandwidth (specially for 4K videos, I would say it's essential).