QoS with LTE connection

Hi!

Kinda struggling with correct configuration path for my home.

I have SXT LTE with 4g connections and hAP ac router.
Searched for QoS guides and many of them suggests per client type limits. It doesn’t line up well for me.
Found some other guide here https://r1ch.net/blog/routerboard but it rather bases on fixed connection speed.

My main usage for home is IPTV, some video streaming services, gaming and rest is what kids use web, mail and youtube.

Where to do QoS config on SXT or on hAP router? And what kind of connection limits should I use, because there is no max limits on down/upload on LTE connection?

As you said, with LTE / 3G / 4G etc it is very difficult to get a max limit, so not good for QoS.

Rather look into bandwidth limit, then as example, do a bandwidth test, limit kids to half of this and other ± half for yourself, or something to that effect

Will try to go trial/error way.
Just one question on which interface and on which device I should do QoS?
Intuition says that on SXT ether1 interface as it would limit WAN traffic.
lte1 interface rather have some load by default, it Tx without anything connected is about 200-1000kbps.
Maybe on wifi routers WAN port, so LAN traffic isn’t affected by that.