Re: Can't Connect To CP4

Ray Gralak

I see that you got it working, but for the benefit of others that might have the same problem:

Connecting directly to a device with an Ethernet cable usually requires that
you set up your laptop to use APIPA (Automatic Private IP addressing
No, I have not seen that referenced anywhere. How do I do that?
It depends on whether your computer/laptop sees a DHCP server or not (e.g., a home WiFi router).

If the computer sees a DHCP server, and the computer is set up to use DHCP, the LAN port may get set to a subnet different than 169.254.x.x, so you probably won't be able to detect the CP4.

Some choices:

1. You can either turn off the WiFi router and reboot your computer. This should allow the LAN port to default to APIPA addressing. If it doesn't, you can change the settings manually.

2. You can manually change the computer LAN Port's TCP/IP V4 settings to use IP subnet, with subnet mask (or Subnet Prefix Length = 16).

Remember to save and restore your settings afterward!

3. If you have a DHCP server, instead of connecting your computer directly to the CP4, you could connect the CP4 to your LAN via Ethernet cable. Note that WiFi won't work by default as it will not have been configured yet.

After connecting the Ethernet cable, power cycling the CP4 should allow the CP4 to acquire an IP address on your LAN via DHCP. Your computer, which will also on the LAN, should then be able to detect/connect to the CP4 via Ethernet.

-Ray Gralak
Author of PEMPro
Author of APCC (Astro-Physics Command Center):
Author of Astro-Physics V2 ASCOM Driver:

-----Original Message-----
From: [] On Behalf Of
Sent: Monday, November 30, 2020 8:46 AM
Subject: Re: [ap-gto] Can't Connect To CP4

Hello Ray,

No, I have not seen that referenced anywhere. How do I do that?


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