Home Networking

Put a cheap 4-port gigabit ethernet switch at the observatory end of the existing cable then if the switch in the house is LAN-connected that new observatory switch will provide wired internet access too. Then plug a patch cable from the new switch to your equipment's original ethernet connection port to run it, too.

Plug a wifi AP into the observatory switch for added wireless access there, too.

Ethernet cables do not "sort out" and treat data communications differently by any kind of categorization. They will transmit any kind of valid data, without discrimination of the source. Internet traffic is not special and does not need to be treated any differently. It just happens to come from farther away.

So you can use your one cable to have the observatory communicate to any amount of devices, from your home or from the Internet, as long as your network topology and settings are configured to do so. Most likely, yours already is. You can test this by "pinging" your observatory equipment's IP Address from the PC controller inside your home.

I have a telescope that uses a CAT 5 crossover cable, but it is NOT ethernet. Two pins are 12 volt power, and other pins tell the motors which way to slew, and report back to the controller how far they've traveled.

Look at the pinout, but unless it's talking ethernet, you'll need two cables to do both.

How does your observatory control work? Is it using proprietary analog signals on that Cat6 cable, is it using RS-232 serial, is it running IP, is it using a non-IP protocol but still ethernet?

By the sounds of it, yeah, just pop a switch on the other end and a cable from that to the observatory then use any of the other ports on the new switch for any other devices you want on the network. If I understand what you're saying it's all IP based, so it should work transparently.

As others said: if it speaks also Ethernet then you can mix. If it just uses Cat cable and RJ45 plugs you can‘t mix.

Hope the observatory is never struck by lightning.