What router are you using?
It's not possible to force connection to a specific band, the connection manager will prefer whatever provides the strongest signal. You might find that setting wireless regulatory domain helps the client device see all frequencies available on the router.
I think rosede means the frequency settings in the router menu. I also have such options.
Can the WiFI hotspot frequency be forced? When using the LibreELEC as AP i mean.
Nope. The hotspot is intentionally simple and doesn't support much more than ON/OFF. If you need router features, you need to get a router 
Nope. The hotspot is intentionally simple and doesn't support much more than ON/OFF. If you need router features, you need to get a router
Ah what a bummer!
I have just replaced my router and the new one does not have WiFi, i figured i could be using this tethering (with decent speeds) while am awaiting the new WiFi puck. 
