⚠ Always install the ASCOM driver version, not just the plain USB driver. The ASCOM driver includes the USB driver inside it. Install ASCOM Platform before any camera drivers.

Your choice — but it is all or nothing. AstroMax solves on its own, so you can skip ASTAP completely. If you do choose it, then everything listed below is required for it to work: the ASTAP application and a star catalogue (H18 for most people), installed into ASTAP’s own data folder, with the path to astap.exe set in AstroMax. Half an installation will not guide, will not solve, and will cost you the night.

Your choice — but it is all or nothing. AstroMax Guide does the same job inside the program, so you can skip PHD2 completely. If you do choose it, then everything listed below is required for it to work: PHD2 itself, an equipment profile with your guide camera and mount, the server enabled (Tools → Enable Server), and AstroMax linked to it on port 4400 — and AstroMax must not be holding the guide camera at the same time. Half an installation will not guide, will not solve, and will cost you the night.

⚠ Guide camera ownership: PHD2 holds the guide camera. AstroMax must NEVER simultaneously connect to it. For non-multi-client cameras (ToupTek, QHY, Atik, Player One, SVBony, Altair) this is critical — two programs cannot share the camera. If AstroMax's Guide panel shows the camera connected in AstroMax itself, disconnect it before starting PHD2.

Your choice — but it is all or nothing. AstroMax reaches your drivers by itself, so you can skip the server completely. If you do choose it, then everything listed below is required for it to work: the server running, your devices added inside it, 64-bit mode switched on for cameras over ~20 MP, and AstroMax pointed at its address — started either by hand or by the switch in Devices → Auto-Start. Half an installation will not guide, will not solve, and will cost you the night.

⚠ Cameras over about 20 megapixels: run ASCOM Remote in 64-bit. ASCOM requires the server to hold every image as 4 bytes per pixel, whatever the camera's real bit depth. That is a single block of roughly 103 MB for a 26 MP sensor (IMX571 — ATR2600, ASI2600) and 233 MB for a full-frame 61 MP sensor (IMX455 — ASI6200). A 32-bit server has only 2 GB of address space and a heap that is never compacted, so after a handful of frames it cannot find room and downloads start failing with System.OutOfMemoryException. Frames are lost at random, then every frame.

Fix: ASCOM Remote Server → Setup → Server Configuration 2 → tick “Run as 64bit application (64bit OS only)” → OK → fully close and restart the server. Task Manager should no longer show (32 bit).

If the camera then refuses to connect, its ASCOM driver is 32-bit only and cannot be loaded by a 64-bit server. Turn the setting back off — nothing is harmed — and use the camera's direct-SDK path in AstroMax instead (Camera panel → Camera brand), which bypasses ASCOM Remote altogether.

⚠ Firewall: If AstroMax cannot connect, check Windows Firewall. Allow both inbound and outbound connections on port 11111 for ASCOM.RemoteServer.exe.

# Test Alpaca connection in your browser or PowerShell:
Invoke-RestMethod http://localhost:11111/api/v1/camera/0/connected
# Expected: { "Value": true, "ErrorNumber": 0, ... }