just ditch this, dlink has been absolutely horrible with too many blunders and still havent changed.

If you want 10Gb/s theres a cheap way to do it. Mikrotik has 16 port fully managed SFP+ switch for 400USD, combined with SFP+ PCIe mellanox cards 2nd hand, about $30 USD each, grab decently priced 1-5M SFP+ direct cables, about $10-$20 each.

Both 10Gbe and SFP+ get more expensive with range. 10Gbe requires CAT 6 up to 50M, Cat 6A up to 100M, SFP+ bandwidth is ensured which is something that cant be said for those cables claiming to be cat6/cat6a.

If you just want a reliable wifi router that is more secure, ditch your dlink and get another brand. plenty of good non dlinks out there. In my own setup, only the modem is the weak link but i cant replace that without losing VOIP.

tp link seems to be having reliability issues i suppose, but netgear, asus and linksys are much better.

However my setup uses mikrotik as router, asus as wifi AP and never ever hangs or drops.

The problem with your tv box is the speed of the tv box. Check the hardware specs of your tv box. If it is a 3rd party tv box, check that the firmware hasnt been riddled with malware/backdoors.