My family has two 1TB Decks and both have connection issues, especially with 5G (does not work). Local Steam network transfer is slow as well, but blazing fast on LCD Decks and Ally. At least 2.4G works for the most part.
Not messing with my router, since every other device in the house works great. Dev option of disabling power saving for Wi-Fi did not help.
Try Redream. It’s way better, IMO. Redream runs 60 FPS even on lower-mid level ARM chips.