New mac won't maintain WPA2 personal wifi hotspot

To be clear

I create a WPA2 wifi network with the new mac mini... i create a password...Turn it on/share... Keeps defaulting to no password/open network - savvy and also have had Apple IT expert assist to no avail.

the mini is hardwired from the modem via ethernet cable, then the mac mini is being set up as the wifi hotspot.

there are no routers involved.

sharing my internet connection on the WiFi

Would've just called it a day and use the speculum modem for that, but since they upgraded my modem, they told me they would charge me more to use it as such.

not exactly... the cable provider wants to charge me more if i use THEIR modem as a hotspot. really lame. So I have my mini hooked up to it with ethernet, my TV, another device and another much older mac. on THAT mac i can only use the outdated WEP (not very secure) network as it's too old for WPA2... so although i have the warnings on all my devices that it's not especially secure, at least it has a password requirement, unlike my mini which won't maintain its WPA2 setting.

The internet provider doesn't require any registration of devices to use it... it's just plug and play.

my mini also only has the option of WPA2 or nothing... but like i said, every time i try to set it up as a WPA2 it doesn't stick... my previous mac didn't do that. I don't suspect a virus, but it certainly behaves like one.