I have had this problem in the past. This has 100% completely fixed the problem for me. If it doesn't work for you - there is no way I can imagine why. I live in the boonies - way in the boonies - WAY WAY out there. No other internet is an option. Since having an iPhone with a hotspot, I have always had issues maintaining a CONSTANT wifi connection to my Lenovo Laptop running on Windows 10. I tried to toggle switches, reset networks, yada yada. I even tried to tether my phone to my PC with the cord thinking that would help... So, fast forward to my getting a brand new phone when the iPhone 12's hit the scene.
So, anway... here ya go --
I have an iPhone 12 Pro Max. I am still using the iP12PM, every day, and I use the hotspot as my only internet source.
It does not disconnect until I manually do it from my PC's wifi switch, OR from the toggle switch in the phones 'Personal Hotspot' settings folder, OR the shortcut menu's green command button.
I added my phone to my computer as a WIRELESS NETWORK DEVICE! :
---Control Panel\All Control Panel Items\Devices and Printers
---"Add a Device" (top left, directly below the toolbar)
---Bluetooth - ON - for iPhone
---Follow prompt wizard, this will setup your iPhone as a "Bluetooth Access Point".
---Save a shortcut of the 'iPhone' that is now visible in the device list to your desktop for easier access.
When you're ready to use the hotspot, make sure you have the Personal Hotspot toggle ON from the settings menu and your iPhone's bluetooth on.
(You only have to do this the one time if you leave it on all the time, you won't need to even mess with your phone - like as long as it's within bluetooth connection rage, you'll connect every time)
When you want to connect to your hotspot:
---Right click on the device on your desktop, like right click on "so-and-so's iPhone" and the second option should read "Connect Using... >"
Hover this option, and choose "Access Point"
Bam. Now your network connection icon will look like the icon when connected to the internet via an Ethernet connection.
When you right click on the icon and "Open Network & Internet Settings" the network page will show the connection diagram
Your Computer Icon -- BT Connection via Private Network -- Internet Ball.
This will fix the problem. The only other issue that could occur is if maybe you chose the wrong kind of network adapter option when setting up the Access Point via the setup wizard. You can change it to bluetooth access on this same page in settings, by "change adapter options".
Like I've already stated, I got this iPhone 12 Pro Max in the late fall of the year it came out, I set it up to use on my Lenovo Laptop with this method THE SAME DAY I got it and I have never ONCE had the problem of the internet auto-disconnecting since doing so.
If I turn on the hotspot and connect wirelessly instead, I will 100% get booted off over and over.
It does not happen when you do it as an Access Point via Bluetooth. :D
So...
Anyway, happy internet browsing!