WIFI Hotspot (ether-wifi) 5Gghz low power

RPI 1 B+ with Alfa ac wifi adapter working as Hotspot, PI is hard wired to router.

Trying to get WIFI adapter to only use 5Ghz and to transmit on very low power… for very short range 5ghz hotspot.

Can someone advise where I can look to change settings ?

Connman is the network manager used in OSMC. I’m not aware of it having the ability to configure tx-power but you should be able to research this for yourself.