謝謝大家！我們目前的做法是將家中Router的5G Wifi從 AC/N改成 A/N，然後我家安卓電視的網路有所改善。
這靈感來自CQMantis的貼文，他提到：
Hello,
Have faced similar problem with "Xiaomi Mi A2 Lite" and I've fixed it by changing 5G band from AC to A/N (in my case) worked fine, but once I change to A/N/AC doesn't works (my router MikroTik AC Lite)
Hope helps for somebody
https://xdaforums.com/t/wifi-proble.../#post-79451427

PS：
【轉貼維基百科】
Wi-Fi 4 802.11n 2008 72- 600 2.4/5
Wi-Fi 5 802.11ac 2014 433- 6,933 5
Wi-Fi 6E 802.11ax 2020 574- 9,608 6
https://zh.wikipedia.org/wiki/IEEE_802.11n