Just wanted to heartily thank everyone for this thread, as "the most simple, staring-you-in-the-face", can sometimes be the most sublime and hard-to-see. On my Samsung J7, I never realized there was a change possible to "allow all devices to connect". I must have inadvertently hit it, and switched it to "allowed devices only", and therein was/is my problem.
Even after talking with my phone service's Customer Support Team and having them try and walk-me-through-it, this most basic of problem was never discovered. Then I have spent countless (hours now) and tried so many "other fixes", internet searches, scratching-my-head, feeling so frustrated that I'm about to "pop", and then I see this most basic of instruction and advice. Even after reading it, I still didn't get-it, b/c on my phone, it doesn't look like something you'd "touch-to-change", it it looks like a fixed section that is indicated "allowed devices only" and that didn't mean much to me, since I'm not that well versed in this protocol and have never dealt with hot-spot issues before, other than, the first time I purchased a better plan that was inclusive of using my phone's hot-spot as a connection point, it worked find and like-a-charm, only to NOT WORK some weeks later, and then this huge frustration and head-ache. I became confused, thinking it meant "allow my phone to be a connection", not realizing it meant, "devices that will connect through the phone". BUT, I was onto the imputing of the MAC address from doing previous research on the internet, only I was imputing the wrong MAC address, that of the Wireless LAN Adapter, but not the Wifi wireless one! It was only when reading this thread, and seeing these God-saving post about "making sure this section is set to all devices", that it showed my correct MAC address. Again, I had the wrong MAC address, and for those of you who need to know how to find your correct MAC address, go to:
type "run" without the quotation marks into your Cortana (Windows-10), or search box for older Windows Versio, and hit enter...
then type: ipconfig /all (notice the space after the ipconfig) then hit enter, then you'll see the ip addresses of so many of your computer's adapters. You want to find: Wireless LAN Wi-Fi Adapter, and see where it says "physical address", and that's your MAC address that you need to input into your smart-phone, IF you want to limit your hot-spot access to your devices only. In learning about all this, and being in a very public space, I noticed that x2 other people had signed-onto my hot-spot WiFi before I became "wise to the ways here", and was able to input the MAC address and have only this laptop I'm typing-on now, gain access. Maybe if your at home or something, you can get-away with "allowing all devices" to connect, but not where I am, NOT a good idea.
At any rate, sorry for the long words, but it was the "most basic and simple thing" of suggestions to "allow all devices" that enabled me to figure-out-my-problem, gain knowledge, and use my phone's hot-spot to get good internet access.
I'm grateful to all here for that, and thus the long post, hoping this helps-out someone else too!
Feeling happy and grateful now! EOM!