AutoHotspot

Keeps the Windows Mobile hotspot switched on: it starts at every sign-in, turns Wi-Fi on when it's off, retries until the network is ready, and switches the hotspot back on within seconds whenever Windows turns it off. It also warns you when the hotspot's IP range collides with another network on your PC, which Windows never tells you about, and on Windows versions that allow it can move the hotspot to a free range.

Download

Download AutoHotspot.exe (64-bit Windows 10 version 2004 or later, or Windows 11)

One file, no installer and no .NET needed. Put it anywhere you like, such as your Documents folder, run it, and switch it on. It doesn't need administrator rights for everyday use (only changing the hotspot IP asks for permission), and uninstalling means switching it off in the dialog and deleting the file.

The exe isn't code-signed, so the first time you run it Windows shows "Windows protected your PC". Click More info, then Run anyway. You can check the download against the SHA256 listed on the release page:

Get-FileHash .\AutoHotspot.exe -Algorithm SHA256

Why

Windows has no built-in "always on" option for Mobile hotspot. After a restart it stays off, it won't start while Wi-Fi is switched off, and its power-saving setting turns it off when no devices are connected. AutoHotspot takes care of all three.

How it works

AutoHotspot is a single small exe with three modes:

Started as	What it does
AutoHotspot.exe	Opens a dialog with an Enabled / Disabled toggle and live status.
AutoHotspot.exe --startup	Runs in the background with a tray icon and keeps the hotspot on.
AutoHotspot.exe --set-hotspot-ip a.b.c.d	Used internally by Change IP... (see Hotspot IP conflicts). It runs elevated after a permission prompt, changes the hotspot address and exits.

When you enable it, the dialog:

1. Adds a sign-in entry under HKCU\Software\Microsoft\Windows\CurrentVersion\Run that runs "<path>\AutoHotspot.exe" --startup. No administrator rights are needed.
2. Starts the background instance right away, so you don't have to restart.

Every 5 seconds the background instance:

1. Turns the Wi-Fi radio on if it's off (Windows.Devices.Radios).
2. Finds a connection to share: the internet connection first, then any other connected network Windows allows sharing.
3. Starts the hotspot if it isn't on (Windows.Networking.NetworkOperators.NetworkOperatorTetheringManager).

It never gives up. At sign-in the adapters and network often take a while to come up, so it keeps trying and starts the hotspot as soon as the connection is available.

Notifications

AutoHotspot shows at most two notifications about the hotspot itself per sign-in:

• Once when the hotspot couldn't be started yet, to say it keeps trying.
• Once when the hotspot finally comes on after those retries.

Later restarts of the hotspot (for example after Windows' power saving turns it off) happen silently.

A hotspot IP problem (next section) gets its own notification, once per distinct problem per sign-in.

Hotspot IP conflicts

The Windows hotspot hands out addresses from one fixed range, 192.168.137.0/24 by default. If your PC is also connected to a network, VPN or virtual adapter in the same range, the hotspot keeps dropping or its devices can't reach anything, and Windows doesn't say why. Typical cause: an IT department that assigned 192.168.137.x addresses, the range Microsoft reserves for the Mobile hotspot. IT should not use 192.168.137.x; AutoHotspot is a workaround for when it does.

The background instance checks this at sign-in and again whenever Windows reports that an IP address changed (not on a timer). It compares the hotspot range against:

• the IPv4 address of every other network adapter (VPN adapters included), and
• the routing table, so a VPN route that covers the range counts too.

It reads the range the hotspot is set to from HKLM\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters (ScopeAddress, falling back to Microsoft's default 192.168.137.1) and the address the hotspot's virtual adapter (for example Local Area Connection* 10) really has. It also reports when the two differ, which happens when the setting was changed but the Windows sharing service (SharedAccess) was not restarted, or when Windows ignores the setting (see below).

When it finds a problem, a notification names the adapter or route and the subnet it collides with. The same problem is announced once per sign-in. Click the notification, use Change hotspot IP... in the tray menu, or press Change IP... in the dialog (which also shows the current hotspot IP and flags problems in red). When there is no problem, Change IP... says so and changes nothing.

Recent Windows 11 versions can't move the hotspot range. On Windows 11 24H2/25H2 (build 26100 and later) the Mobile hotspot always gives connected devices 192.168.137.x, whatever ScopeAddress says; even a reboot doesn't change that. On those versions Change IP... notices that the adapter kept its old address, puts the previous setting back and tells you. The conflict warning still works, and the only real fix is for the network or IT department not to use 192.168.137.x.

Change IP... does this:

1. Picks a new /24 that overlaps nothing on the PC (all adapters and all routes): 192.168.50.x first, then 192.168.51.x and so on up to 192.168.99.x, then 10.77.50-99.x and 172.30.50-99.x. If the address in the registry is already free and only wasn't applied yet, it offers that one instead.
2. Shows it to you and asks for confirmation. Nothing happens before you say yes.
3. Asks Windows for permission (UAC) and runs an elevated copy of the exe that: switches the hotspot off, stops the SharedAccess service, writes both ScopeAddress and ScopeAddressBackup, starts the service, switches the hotspot on, and finally reads the hotspot adapter's real address again.

If a step fails, or the adapter still shows the old address afterwards (Windows ignored the setting), the previous registry values are restored and the service and hotspot are brought back, so a failed change never leaves sharing stopped or a setting behind that Windows doesn't use. The background keep-alive loop pauses while the change runs, so it doesn't start the hotspot halfway through.

Devices connected to the hotspot reconnect on their own after the change. The hotspot name and password stay the same.

Tray icon

While the background instance runs it shows a tray icon. Hover over it for the current status. Right-click it to:

• Open AutoHotspot (opens the dialog)
• Start hotspot / Stop hotspot (no automatic restart): Stop switches the hotspot off and keeps it off; the tray icon stays. Start switches it on again and resumes keeping it on. A stop lasts until you choose Start or until the next sign-in.
• Change hotspot IP... (see Hotspot IP conflicts)
• Open log
• Exit until next sign-in (closes the background instance and its tray icon; the hotspot is left as it is)

When you disable it in the dialog, the sign-in entry is removed and the running background instance stops.

Good to know

• Sign-in, not boot. The hotspot API needs a signed-in user, so AutoHotspot starts when you sign in to Windows.
• Hotspot name and password are set in Windows: Settings > Network & internet > Mobile hotspot. The dialog has a link to that page.
• Moving the exe: open the dialog once from the new location. If it's enabled, the sign-in entry is updated to the new path.
• Administrator rights: only the hotspot IP change needs them, through a normal Windows permission prompt. Declining it changes nothing.
• Log file: %LOCALAPPDATA%\AutoHotspot\log.txt. Only state changes are logged, and the file is rotated at 1 MB.
• Radio permission: if the log says Windows doesn't allow controlling radios, check Settings > Privacy & security > Radios.

Requirements

• Windows 10 version 2004 (build 19041) or later, or Windows 11
• A Wi-Fi adapter that supports Mobile hotspot
• .NET 8 Desktop Runtime, unless you publish self-contained

Building

Open AutoHotspot.sln in Visual Studio 2022 (17.8 or later), or run:

dotnet build AutoHotspot.sln -c Release

To publish a single exe that doesn't need .NET installed:

dotnet publish AutoHotspot/AutoHotspot.csproj -c Release -r win-x64 --self-contained -p:PublishSingleFile=true

The pure subnet-overlap and range-picking logic has tests in AutoHotspot.Tests, a plain console runner (no test framework, since the project uses no NuGet packages). They don't touch the registry, adapters or services:

dotnet run --project AutoHotspot.Tests

The project uses no NuGet packages. The Windows Runtime APIs come from the net8.0-windows10.0.19041.0 target framework.

License

MIT