1.
iptvs, netflix, etc.
It is best to connect your main streaming hardwares via ethernet cable
Actually, connect as many as you can via cable and if possible only your mobile devices is going via WLAN.
If you need more cable ports, get a switch.
2.
Check for the WLAN channels in your neighbourhood, use the least crowded one.
3.
WLAN range is special, even if you already have the best router out there. Check if you need Range extender a.k.a. repeater or mix your networking with PowerLAN, etc.
WLAN extender is bad for your total WLAN bandwidth but sometimes you need this solution.
4.
5GHz WLAN is stable ad fast but has some problem passing through thick walls. Be smart! Combine with 2.4GHz.
5.
Check the router for MIMO channels, the more the better.